Expand Phabricator docs slightly

[scott-0]

Summary

Here's a patch to the Phabricator web UI instructions in the docs that adds a couple missing button clicks and is a somewhat round-about way of asking a couple questions:

• What is was meant by the pre-exisitng TODO?
• Should the Repository and Project fields be used?

When I get the answers I'll update the patch. Thanks.

[probinson]

The TODO looks like it has been there since Manuel created the doc in 2012. Probably not even Manuel remembers what he thought was missing, after all this time.

Leaving the Project and Repository blank seems to work pretty well. :-)

docs/Phabricator.rst

63

Maybe "browse to" instead of "choose" (the button does say Browse).
Of course you can always just type in the filename but I never do it that way.

[klimek]

Thx!

docs/Phabricator.rst

63–65

Ugh, no idea what I thought...

64

We've set up a single large repo, so leaving that is fine.

73

Nope. We only have a single repo.

[scott-0]

Thanks for the reviews; comments addressed.

[klimek]

lg. thx

[scott-0]

committed as r241161

docs/Phabricator.rst

 to upload your patch):
 
 * ``git diff -U999999 other-branch``
 * ``svn diff --diff-cmd=diff -x -U999999``
 
 To upload a new patch:
 
 * Click *Differential*.
-* Click *Create Diff*.
-* Paste the text diff or upload the patch file.
-  Note that TODO
+* Click *+ Create Diff*.
+* Paste the text diff or browse to the patch file. Click *Create Diff*.
+* Leave the Repository field blank.
 * Leave the drop down on *Create a new Revision...* and click *Continue*.
 * Enter a descriptive title and summary.  The title and summary are usually
   in the form of a :ref:`commit message <commit messages>`.
 * Add reviewers and mailing
   lists that you want to be included in the review. If your patch is
-  for LLVM, add llvm-commits as a subscriber; if your patch is for Clang,
+  for LLVM, add llvm-commits as a Subscriber; if your patch is for Clang,
   add cfe-commits.
+* Leave the Repository and Project fields blank.
 * Click *Save*.
 
 To submit an updated patch:
 
 * Click *Differential*.
-* Click *Create Diff*.
-* Paste the updated diff.
+* Click *+ Create Diff*.
+* Paste the updated diff or browse to the updated patch file. Click *Create Diff*.
 * Select the review you want to from the *Attach To* dropdown and click
   *Continue*.
-* Click *Save*.
+* Leave the Repository and Project fields blank.
+* Add comments about the changes in the new diff. Click *Save*.
 
 Reviewing code with Phabricator
 -------------------------------
 
 Phabricator allows you to add inline comments as well as overall comments
 to a revision. To add an inline comment, select the lines of code you want
 to comment on by clicking and dragging the line numbers in the diff pane.
 When you have added all your comments, scroll to the bottom of the page and