chore: update bzlmod example

[alexeagle]

• set the bazel version rather than recommend 'floating' last green
• recommend enabling bzlmod in .bazelrc
• simplify 'try it' commands
• MODULE.bazel.lock files now produced since it's bazel 6.3

[gregestren]

Deferring to @Wyverald but let me know if you need permissions help with the .bazelci/ diff.

[alexeagle]

I'll remove MODULE.bazel.lock files as well, since there are staleness bugs with bazel 6.3.0 per @fmeum