Merge pull request #5628 from royalharsh/master

Fixes #5561

CONTRIBUTING.md

@@ -45,9 +45,13 @@ In order to run most of the available tests, one would need to run:
 
 `./tools/run_tests/run_tests.py`
 
-If you want to run all the possible tests for any of the languages {c, c++, node, php, python}, do this:
+If you want to run tests for any of the languages {c, c++, csharp, node, objc, php, python, ruby}, do this:
 
-`./tools/run_tests/run_tests.py -l <lang> -c all`
+`./tools/run_tests/run_tests.py -l <lang>`
+
+To know about the list of available commands, do this:
+
+`./tools/run_tests/run_tests.py -h`
 
 ## Adding or removing source code