feat(git): add grst alias for `git restore --staged` (#8932)

Closes #8932

plugins/git/README.md

@@ -136,6 +136,7 @@ plugins=(... git)
 | grs                  | git restore                                                                                                                      |
 | grset                | git remote set-url                                                                                                               |
 | grss                 | git restore --source                                                                                                             |
+| grst                 | git restore --staged                                                                                                             |
 | grt                  | cd "$(git rev-parse --show-toplevel \|\| echo .)"                                                                                |
 | gru                  | git reset --                                                                                                                     |
 | grup                 | git remote update                                                                                                                |

plugins/git/git.plugin.zsh

@@ -236,6 +236,7 @@ alias grrm='git remote remove'
 alias grs='git restore'
 alias grset='git remote set-url'
 alias grss='git restore --source'
+alias grst='git restore --staged'
 alias grt='cd "$(git rev-parse --show-toplevel || echo .)"'
 alias gru='git reset --'
 alias grup='git remote update'