Update configuration docs to discuss the exec and host configurations…
Update configuration docs to discuss the exec and host configurations…

…, and how they are different and similar.

Part of improving configurability documentation, #11967.

Closes #11991.

PiperOrigin-RevId: 328330191

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