[lit] Change --show-{tests,suites} to exit after printing.

 - This is a more sensible behavior than printing and also running tests.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188009 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/CommandGuide/lit.rst b/docs/CommandGuide/lit.rst
index 5e986c8..4d84be6 100644
--- a/docs/CommandGuide/lit.rst
+++ b/docs/CommandGuide/lit.rst
@@ -149,7 +149,11 @@
 
 .. option:: --show-suites
 
- List the discovered test suites as part of the standard output.
+ List the discovered test suites and exit.
+
+.. option:: --show-tests
+
+ List all of the the discovered tests and exit.
 
 EXIT STATUS
 -----------