[lit] NFC: Add missing option descriptions to documentation

[t-msn]

Summary

Some options are missing in the documentation.
Add them in accordance with help messages.

[t-msn]

I'm not sure who is the code owner of this. Could you please review this as I see you have previously review similar commit?

[cmatthews]

LGTM. Thanks!

[t-msn]

Thank you very much. Could I also ask you to commit this patch as I don't have right?

[t-msn]

Gentle ping, or can anyone help me to commit this? Thanks.

[t-msn]

Friendly ping as this seems to have forgotten. Thanks.

llvm/docs/CommandGuide/lit.rst

  locate the source line of the failed command.
  This option implies ``--verbose``.
 
 .. option:: -a, --show-all
 
  Show more information about all tests, for example the entire test
  commandline and output.
 
+.. option:: -o PATH, --output PATH
+
+ Write test results to the provided path.
+
 .. option:: --no-progress-bar
 
  Do not use curses based progress bar.
 
+.. option:: --show-excluded
+
+ Show the names of excluded tests.
+
+.. option:: --show-skipped
+
+ Show the names of skipped tests.
+
 .. option:: --show-unsupported
 
  Show the names of unsupported tests.
 
+.. option:: --show-pass
+
+ Show the names of passed tests.
+
+.. option:: --show-flakypass
+
+ Show the names of passed with retry tests.
+
 .. option:: --show-xfail
 
  Show the names of tests that were expected to fail.
 
 .. _execution-options:
 
 EXECUTION OPTIONS
 -----------------

  certain tests.
 
 .. option:: --time-tests
 
  Track the wall time individual tests take to execute and includes the results
  in the summary output.  This is useful for determining which tests in a test
  suite take the most time to execute.
 
+.. option:: --no-execute
+
+ Don't execute any tests (assume PASS).
+
+.. option:: --xunit-xml-output XUNIT_XML_OUTPUT
+
+ Write XUnit-compatible XML test reports to the specified file.
+
+.. option:: --resultdb-output RESULTDB_OUTPUT
+
+ Write LuCI ResuldDB compatible JSON to the specified file.
+
+.. option:: --time-trace-output TIME_TRACE_OUTPUT
+
+ Write Chrome tracing compatible JSON to the specified file.
+
+.. option::  --allow-empty-runs
+
+ Do not fail the run if all tests are filtered out.
+
 .. option:: --ignore-fail
 
  Exit with status zero even if some tests fail.
 
 .. option:: --no-indirectly-run-check
 
  Do not error if a test would not be run if the user had specified the
  containing directory instead of naming the test directly.

 .. option:: --show-suites
 
  List the discovered test suites and exit.
 
 .. option:: --show-tests
 
  List all of the discovered tests and exit.
 
+.. option:: --show-used-features
+
+ List all of the used features in tests and exit.
+
 EXIT STATUS
 -----------
 
 :program:`lit` will exit with an exit code of 1 if there are any FAIL or XPASS
 results.  Otherwise, it will exit with the status 0.  Other exit codes are used
 for non-test related failures (for example a user error or an internal program
 error).