remove note about --watch (until we have it again)

Author: ryanflorence

CONTRIBUTING.md

@@ -32,7 +32,6 @@ always be in sync.
   specs directory.
 - `npm test` will do the same but doesn't watch, just runs the tests.
 - `script/build-examples` does exactly that.
-- `script/build-examples --watch` is a little more useful.
 
 ### Build