git: change docs for git_main_branch

Also remove unnecesary dramatic remark

plugins/git/README.md

@@ -209,12 +209,12 @@ These are aliases that have been removed, renamed, or otherwise modified in a wa
 ### Current
 
 | Command                | Description                                                                            |
-|:-----------------------|:-----------------------------------------------------------------------------|
+|:-----------------------|:---------------------------------------------------------------------------------------|
 | `grename <old> <new>`  | Rename `old` branch to `new`, including in origin remote                               |
 | current_branch         | Return the name of the current branch                                                  |
 | git_current_user_name  | Returns the `user.name` config value                                                   |
 | git_current_user_email | Returns the `user.email` config value                                                  |
-| git_main_branch        | Returns the name of the main branch: `master` if it exists, `main` otherwise |
+| git_main_branch        | Returns the name of the main branch: from origin or from local branches, else 'master' |
 
 ### Work in Progress (WIP)
 

plugins/git/git.plugin.zsh

@@ -25,8 +25,7 @@ function work_in_progress() {
   fi
 }
 
-# Get the default 'main' branch
-# Marc(2020-07-11): I hope to be able to remove this someday
+# Get the default 'main' branch: from origin, from local branches, or else just 'master'
 function git_main_branch() {
   # Get default branch from the origin remote
   local branch