Branch strategies

write some guidelines on handling and updating branches. Potentially including:

* making it clear to merge not rebase when catching up to main
* use of branch of branch to do sequential work and encourage smaller tickets - cherry picking, does deleting the initial branch make a difference on a rebase?
* encourage use of forks as good playgrounds for investigative work.

The issue does not name a target file or existing documentation page. Start by locating the repository's working-practices or contribution guidance, then compare its branch workflow with the requested topics: merging versus rebasing, branch-of-branch workflows, cherry-picking, and forks. Done means the guidance covers these points clearly and encourages smaller, investigative changes.

Written by the indexing model from the issue text.