docs: Fix formatting of `GCE_METADATA_HOST` (#890)
docs: Fix formatting of `GCE_METADATA_HOST` (#890)

* Clean docs up

* Update google/auth/environment_vars.py

Co-authored-by: arithmetic1728 <c4f7d4a0274861ca4f6b218744d7bb59b909c33b@users.noreply.github.com>
googleapis/google-auth-library-python,googleapis/google-auth-library-python