Remove toolcache option description from action.yml

Author: mbg

init/action.yml

@@ -15,8 +15,6 @@ inputs:
       - A special value `nightly` which uses the latest nightly version of the
         CodeQL tools. Note that this is unstable and not recommended for
         production use.
-      - A special value `toolcache` which uses the latest version available in the
-        toolcache on the runner.
 
       If not specified, the Action will check in several places until it finds
       the CodeQL tools.