META: management of "lts" branch named like scroll-dev-MMDD

[lispc]

current active branch

scroll-dev-0521

Branch management

We have some diffs not merged into upstream but needed for our integration.
So we periodically fork a branch from upstream main and apply our diffs.
Once the scroll-dev-MMDD is made, only small patch(compatibility guaranteed, including API & perf & tests) & bug fixes will be applied onto(we make PRs against scroll-dev-MMDD branch). If we need big&new features, we fork a new scroll-dev-MMDD branch from upstream main, and rebase(squash or not both ok) our old+new patches.

We should never force push.