Refresh configurable attributes doc.
Refresh configurable attributes doc.

Highlights:

- Update outdated "Starlark flags not yet supported" refs
- Convert "--define" examples to Starlark flags when possible
- Overhaul "native vs. user-defined" core config_setting description
- Use more consistent package naming for examples
- Remove "Short keys" section, which is considered bad practice (creates too much indirection which makes it hard to know what relies on what).

For https://github.com/bazelbuild/bazel/issues/11967

PiperOrigin-RevId: 328335077

werkt/bazel,meteorcloudy/bazel,davidzchen/bazel,ButterflyNetwork/bazel,cushon/bazel,werkt/bazel,ButterflyNetwork/bazel,davidzchen/bazel,perezd/bazel,meteorcloudy/bazel,bazelbuild/bazel,katre/bazel,werkt/bazel,safarmer/bazel,twitter-forks/bazel,davidzchen/bazel,werkt/bazel,safarmer/bazel,werkt/bazel,twitter-forks/bazel,cushon/bazel,bazelbuild/bazel,cushon/bazel,katre/bazel,meteorcloudy/bazel,davidzchen/bazel,safarmer/bazel,bazelbuild/bazel,twitter-forks/bazel,perezd/bazel,perezd/bazel,cushon/bazel,twitter-forks/bazel,meteorcloudy/bazel,safarmer/bazel,meteorcloudy/bazel,ButterflyNetwork/bazel,cushon/bazel,davidzchen/bazel,katre/bazel,katre/bazel,werkt/bazel,davidzchen/bazel,twitter-forks/bazel,meteorcloudy/bazel,davidzchen/bazel,safarmer/bazel,safarmer/bazel,ButterflyNetwork/bazel,perezd/bazel,ButterflyNetwork/bazel,bazelbuild/bazel,twitter-forks/bazel,twitter-forks/bazel,perezd/bazel,meteorcloudy/bazel,cushon/bazel,ButterflyNetwork/bazel,perezd/bazel,bazelbuild/bazel,katre/bazel,katre/bazel,bazelbuild/bazel,perezd/bazel