Correct for new GitHub default branch (#5055)

* Correct for new GitHub default branch

This PR corrects the default branch of GitHub from master to main. This is ne GitHub repository configuration from Oct 1st, 2020

* Update Saving to a Git service.tid

GitLab still uses `master` as default branch.

* Add Kookma plugins as resources

Some of Kookma resources including TW-Scripts, Commander, Trashbin, Todolist has been added.

* Revert "Add Kookma plugins as resources"

This reverts commit 199fce3a08f8e21c776c7e37734b0d36753bb3e8.

editions/tw5.com/tiddlers/saving/Saving to a Git service.tid

@@ -17,7 +17,7 @@ Saving to a Git service is configured in the [[$:/ControlPanel]] in the ''Git Se
 * ''Username'' - (mandatory) the username for the Git service account used for saving changes
 * ''Password'' - (mandatory) the password, OAUTH token or personal access token for the specified account. Note that GitHub permits [[several different mechanisms|https://developer.github.com/v3/#authentication]] for authentication
 * ''Repository'' - (mandatory) the name of the Git repository. Both the owner name and the repository name must be specified. For example `Jermolene/TiddlyWiki5`
-* ''Branch'' - (optional) the name of the branch to be used within the Git repository. Defaults to `master`
+* ''Branch'' - (optional) the name of the branch to be used within the Git repository. Defaults to `main` (~GitHub) or `master` (~GitLab)"
 * ''Path'' - (optional) the path to the target file. Defaults to `/`
 * ''Filename'' - (mandatory) the filename of the target file