Add `bazel` or `starlark` as alias for `python`

[ordishg]

In the supported languages table, the python row lists some file names and extensions that are specific to bazel/starlark. These were added in #1259.

Although the python parser is used, it'd be nice to be able to refer to Starlark code as starlark or bazel rather than python.

I'm happy to make a PR for this if this seems reasonable.

[jeanas]

Yes, sounds fine.