doc: edit LTS material in Collaborator Guide
- Rewrite some material for simplicity and directness.
- Remove outdated LTS material in the Collaborator Guide. (For example, refers to LTS WG for things that are now handled by the Release WG.)
- Minor change to text about force pushing (s/minimize/reduce/).
Checklist
-
make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
documentation is changed or added -
commit message follows commit guidelines