[doc] Apply buildbot worker terminology change: slave->worker

[kwk]

Summary

Recently [1], there was an upgrade to the version of buildbot being
deployed. The new setup will still work with old buildslaves but I
thought it might be a good idea to update the documentation to reflect,
that you now can use a newer buildbot version to when setting up your
worker (formely known as slave).

The upgrade from buildbot 0.8.5 to 2.8.5 went a long with a transition
to a new "worker" terminology [2] which is also reflected by this
change.

[1]: http://lists.llvm.org/pipermail/llvm-dev/2020-October/145629.html
[2]: http://docs.buildbot.net/0.9.12/manual/worker-transition.html

[kwk]

Fixup

[gkistanova]

Thanks, Konrad!

llvm/docs/HowToAddABuilder.rst

 ===================================================================
 How To Add Your Build Configuration To LLVM Buildbot Infrastructure
 ===================================================================
 
 Introduction
 ============
 
 This document contains information about adding a build configuration and
-buildslave to private slave builder to LLVM Buildbot Infrastructure.
+buildbot-worker to private worker builder to LLVM Buildbot Infrastructure.
 
 Buildmasters
 ============
 
 There are two buildmasters running.
 
 * The main buildmaster at `<http://lab.llvm.org:8011>`_. All builders attached
   to this machine will notify commit authors every time they break the build.
 * The staging buildbot at `<http://lab.llvm.org:8014>`_. All builders attached
   to this machine will be completely silent by default when the build is broken.
   Builders for experimental backends should generally be attached to this
   buildmaster.
 
 Steps To Add Builder To LLVM Buildbot
 =====================================
-Volunteers can provide their build machines to work as build slaves to
+Volunteers can provide their build machines to work as build workers to
 public LLVM Buildbot.
 
 Here are the steps you can follow to do so:
 
 #. Check the existing build configurations to make sure the one you are
    interested in is not covered yet or gets built on your computer much
    faster than on the existing one. We prefer faster builds so developers
    will get feedback sooner after changes get committed.
 
 #. The computer you will be registering with the LLVM buildbot
    infrastructure should have all dependencies installed and you can
    actually build your configuration successfully. Please check what degree
    of parallelism (-j param) would give the fastest build.  You can build
    multiple configurations on one computer.
 
-#. Install buildslave (currently we are using buildbot version 0.8.5).
-   Depending on the platform, buildslave could be available to download and
+#. Install buildbot-worker (currently we are using buildbot version 2.8.5).
+   Depending on the platform, buildbot-worker could be available to download and
    install with your package manager, or you can download it directly from
    `<http://trac.buildbot.net>`_ and install it manually.
 
-#. Create a designated user account, your buildslave will be running under,
+#. Create a designated user account, your buildbot-worker will be running under,
    and set appropriate permissions.
 
-#. Choose the buildslave root directory (all builds will be placed under
-   it), buildslave access name and password the build master will be using
-   to authenticate your buildslave.
-
-#. Create a buildslave in context of that buildslave account.  Point it to
-   the **lab.llvm.org** port **9990** (see `Buildbot documentation,
-   Creating a slave
-   <http://docs.buildbot.net/current/tutorial/firstrun.html#creating-a-slave>`_
+#. Choose the buildbot-worker root directory (all builds will be placed under
+   it), buildbot-worker access name and password the build master will be using
+   to authenticate your buildbot-worker.
+
+#. Create a buildbot-worker in context of that buildbot-worker account. Point it
+   to the **lab.llvm.org** port **9990** (see `Buildbot documentation,
+   Creating a worker
+   <http://docs.buildbot.net/current/tutorial/firstrun.html#creating-a-worker>`_
    for more details) by running the following command:
 
     .. code-block:: bash
 
-       $ buildslave create-slave <buildslave-root-directory> \
+       $ buildbot-worker create-worker <buildbot-worker-root-directory> \
                     lab.llvm.org:9990 \
-                    <buildslave-access-name> <buildslave-access-password>
+                    <buildbot-worker-access-name> \
+                    <buildbot-worker-access-password>
 
-   To point a slave to silent master please use lab.llvm.org:9994 instead
+   To point a worker to silent master please use lab.llvm.org:9994 instead
    of lab.llvm.org:9990.
 
-#. Fill the buildslave description and admin name/e-mail.  Here is an
-   example of the buildslave description::
+#. Fill the buildbot-worker description and admin name/e-mail.  Here is an
+   example of the buildbot-worker description::
 
        Windows 7 x64
        Core i7 (2.66GHz), 16GB of RAM
 
        g++.exe (TDM-1 mingw32) 4.4.0
        GNU Binutils 2.19.1
        cmake version 2.8.4
        Microsoft(R) 32-bit C/C++ Optimizing Compiler Version 16.00.40219.01 for 80x86
 
-#. Make sure you can actually start the buildslave successfully. Then set
-   up your buildslave to start automatically at the start up time.  See the
+#. Make sure you can actually start the buildbot-worker successfully. Then set
+   up your buildbot-worker to start automatically at the start up time.  See the
    buildbot documentation for help.  You may want to restart your computer
    to see if it works.
 
-#. Send a patch which adds your build slave and your builder to
+#. Send a patch which adds your build worker and your builder to
    `zorg <https://github.com/llvm/llvm-zorg>`_. Use the typical LLVM 
    `workflow <https://llvm.org/docs/Contributing.html#how-to-submit-a-patch>`_.
 
-   * slaves are added to ``buildbot/osuosl/master/config/slaves.py``
+   * workers are added to ``buildbot/osuosl/master/config/slaves.py``
    * builders are added to ``buildbot/osuosl/master/config/builders.py``
 
    Please make sure your builder name and its builddir are unique through the
    file.
 
    It is possible to allow email addresses to unconditionally receive
    notifications on build failure; for this you'll need to add an
    ``InformativeMailNotifier`` to ``buildbot/osuosl/master/config/status.py``.
    This is particularly useful for the staging buildmaster which is silent
    otherwise.
 
-#. Send the buildslave access name and the access password directly to
+#. Send the buildbot-worker access name and the access password directly to
    `Galina Kistanova <mailto:[e-mail]>`_, and wait till she
    will let you know that your changes are applied and buildmaster is
    reconfigured.
 
-#. Check the status of your buildslave on the `Waterfall Display
-   <http://lab.llvm.org:8011/waterfall>`_ to make sure it is connected, and
-   ``http://lab.llvm.org:8011/buildslaves/<your-buildslave-name>`` to see
-   if administrator contact and slave information are correct.
+#. Check the status of your buildbot-worker on the `Waterfall Display
+   <http://lab.llvm.org:8011/#/waterfall>`_ to make sure it is connected, and
+   ``http://lab.llvm.org:8011/#/workers`` to see if administrator contact and
+   worker information are correct.
 
 #. Wait for the first build to succeed and enjoy.