[docs] Improve `git cl patch --help`

Change-Id: I001a1baafe2b136bbe89055fec5ae91118332d1c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4660921
Reviewed-by: Andy Perelson <ajp@google.com>
Auto-Submit: Victor Vianna <victorvianna@google.com>
Commit-Queue: Andy Perelson <ajp@google.com>

git_cl.py

@@ -5206,7 +5206,7 @@ def CMDland(parser, args):
 @subcommand.usage('<patch url or issue id or issue url>')
 @metrics.collector.collect_metrics('git cl patch')
 def CMDpatch(parser, args):
-  """Patches in a code review."""
+  """Applies (cherry-picks) a Gerrit changelist locally."""
   parser.add_option('-b', dest='newbranch',
                     help='create a new branch off trunk for the patch')
   parser.add_option('-f', '--force', action='store_true',

man/html/git-cl.html

@@ -890,7 +890,7 @@ patch
 </dt>
 <dd>
 <p>
-  patches in a code review
+  applies (cherry-picks) a Gerrit changelist locally
 </p>
 </dd>
 <dt class="hdlist1">

man/man1/git-cl.1

@@ -114,7 +114,7 @@ interactively find the owners for reviewing
 .PP
 patch
 .RS 4
-patches in a code review
+applies (cherry-picks) a Gerrit changelist locally
 .RE
 .PP
 presubmit

man/src/git-cl.txt

@@ -65,7 +65,7 @@ owners::
   interactively find the owners for reviewing
 
 patch::
-  patches in a code review
+  applies (cherry-picks) a Gerrit changelist locally
 
 presubmit::
   runs presubmit tests on the current changelist