[libc++] Fix the documentation and re-enable documentation CI

[ldionne]

Summary

The documentation CI job is very cheap, so we can afford to keep it
around even with reduced capacity. This commit fixes the documentation
(which had an invalid reference in it) and re-enables that CI step.

[tschuett]

libcxx/docs/index.rst

201

LLVM is moving fast. Do you want to hint at GitHub? There are still bugzilla references in this document,

[• Quuxplusone]

libcxx/docs/index.rst

160

https://github.com/llvm/llvm-project/issues?q=label%3Alibc%2B%2B

[ldionne]

libcxx/docs/index.rst

201

I don't see any references to Bugzilla except for what @Quuxplusone caught above. Did you spot any others?

I think it's OK not to go out of our way to mention GitHub in case that changes in the future, and given that it doesn't add a lot of useful information. They'll see that it's on GitHub when/if they click on the link.

[ldionne]

Remove link to bugzilla

[curdeius]

libcxx/docs/index.rst

160

@ldionne
These are all bugs, nope?
I think it should be https://github.com/llvm/llvm-project/labels/libc%2B%2B (equivalent of https://github.com/llvm/llvm-project/issues?q=label%3Alibc%2B%2B+is%3Aopen).

[ldionne]

libcxx/docs/index.rst

160

Yes, you're right, that seems a bit better. Thanks, doing as post-commit fix.

libcxx/docs/index.rst

 This list contains known issues with libc++
 
 * Building libc++ with ``-fno-rtti`` is not supported. However
   linking against it with ``-fno-rtti`` is supported.
 
 
 A full list of currently open libc++ bugs can be `found here`__.
 
 .. __:  https://bugs.llvm.org/buglist.cgi?component=All%20Bugs&product=libc%2B%2B&query_format=advanced&resolution=---&order=changeddate%20DESC%2Cassigned_to%20DESC%2Cbug_status%2Cpriority%2Cbug_id&list_id=74184
 
 
 Design Documents
 ================
 
 .. toctree::
    :maxdepth: 1
 

 ================
 
 First please review our `Developer's Policy <https://llvm.org/docs/DeveloperPolicy.html>`__
 and `Getting started with LLVM <https://llvm.org/docs/GettingStarted.html>`__.
 
 **Bug Reports**
 
 If you think you've found a bug in libc++, please report it using
-the `LLVM Bugzilla`_. If you're not sure, you
+the `LLVM bug tracker`_. If you're not sure, you
 can post a message to the `libcxx-dev mailing list`_ or on IRC.
 
 **Patches**
 
 If you want to contribute a patch to libc++, the best place for that is
 `Phabricator <https://llvm.org/docs/Phabricator.html>`_. Please add `libcxx-commits` as a subscriber.
 Also make sure you are subscribed to the `libcxx-commits mailing list <http://lists.llvm.org/mailman/listinfo/libcxx-commits>`_.
 

libcxx/utils/ci/buildkite-pipeline.yml

steps:
   #     queue: "libcxx-builders"
   #     os: "linux"
   #   retry:
   #     automatic:
   #       - exit_status: -1  # Agent was lost
   #         limit: 2
   #   timeout_in_minutes: 120
 
-  # - label: "Documentation"
-  #   command: "libcxx/utils/ci/run-buildbot documentation"
-  #   artifact_paths:
-  #     - "**/test-results.xml"
-  #   agents:
-  #     queue: "libcxx-builders"
-  #     os: "linux"
-  #   retry:
-  #     automatic:
-  #       - exit_status: -1  # Agent was lost
-  #         limit: 2
-  #   timeout_in_minutes: 120
+  - label: "Documentation"
+    command: "libcxx/utils/ci/run-buildbot documentation"
+    artifact_paths:
+      - "**/test-results.xml"
+    agents:
+      queue: "libcxx-builders"
+      os: "linux"
+    retry:
+      automatic:
+        - exit_status: -1  # Agent was lost
+          limit: 2
+    timeout_in_minutes: 120
 
   # Tests on non-Unix platforms
   - label: "Clang-cl (DLL)"
     command: "bash libcxx/utils/ci/run-buildbot clang-cl-dll"
     artifact_paths:
       - "**/test-results.xml"
     agents:
       queue: "windows"