Documentation

Summary: Add instruction how to run tests prior to pushing PR'sCloses https://github.com/facebook/infer/pull/145

Reviewed By: @cristianoc

Differential Revision: D2493665

Pulled By: @jvillard

CONTRIBUTING.md

@@ -1 +1,20 @@
-We require contributors to sign our Contributor License Agreement. In order for us to review and merge your code, please sign up at https://code.facebook.com/cla. If you have any questions, please drop us a line at cla@fb.com. Thanks!
+# Contribution Guidelines
+
+## Contributor License Agreement
+
+We require contributors to sign our Contributor License Agreement. In
+order for us to review and merge your code, please sign up at
+https://code.facebook.com/cla. If you have any questions, please drop
+us a line at cla@fb.com. Thanks!
+
+## Submitting Pull Requests
+
+* Please make sure Infer builds: `make -C infer clean <target>`. Refer
+  to the [installation
+  document](https://github.com/facebook/infer/blob/master/INSTALL.md)
+  for details.
+
+* If relevant, add a test for your change. Tests are located at
+  `infer/tests/codetoanalyze/` and
+  `infer/tests/{endtoend,frontend}/`. To run the all tests, execute
+  `./scripts/test.sh`.