Clean up the release plan template a little. (#6254)
Clean up the release plan template a little. (#6254)

* group branch-related tasks
* add tasks related to the "release" branch being "protected"
* note that the "release" branch can be force-pushed (instead of delete/create)
DonJayamanne/pythonVSCode,DonJayamanne/pythonVSCode,DonJayamanne/pythonVSCode,DonJayamanne/pythonVSCode,DonJayamanne/pythonVSCode