Add documentation about using Profile Guided Optimization (PGO)

See discussion: https://github.com/apache/arrow-rs/discussions/6500

Consider adding a note to our documentation somewhere about benefits of using this approach, how to do it, etc.

Start by reading the linked discussion at github.com/apache/arrow-rs/discussions/6500 and inspect the repository's existing documentation structure to find an appropriate location. Document the benefits of Profile Guided Optimization and the steps for using it, with the relevant guidance consolidated in the chosen documentation page.

Written by the indexing model from the issue text.