Update Bazel.gitignore

[symbiont-ji]

• The bazel-* line should not start with a /, as the root of the bazel source tree is not necessarily the root of the repo.
• Gazelle-specific rule: Gazelle has an option to accept several different filenames as BUILD files; they don't even have to be named BUILD.*. It will use the first name in the rule for the files it generates. Some people prefer not to store generated files in the repo, hence this rule.

Reasons for making this change:

Better rules for bazel

Links to documentation supporting these rule changes:

https://bazel.build/ and https://github.com/bazelbuild/bazel-gazelle

If this is a new template:

• Link to application or project’s homepage: TODO

[github-actions]

This PR is stale because there have been no updates in 90 days. It will close after 180 days of inactivity. Leave a comment if you want to keep it open 😄