added git messenger to <leadre>gm

keys/which-key.vim

@@ -156,6 +156,7 @@ let g:which_key_map.g = {
       \ 'j' : ['<Plug>(GitGutterNextHunk)'         , 'next hunk'],
       \ 'k' : ['<Plug>(GitGutterPrevHunk)'         , 'prev hunk'],
       \ 'l' : [':Git log'                          , 'log'],
+      \ 'm' : ['<Plug>(git-messenger)'             , 'message'],
       \ 'p' : [':Git push'                         , 'push'],
       \ 'P' : [':Git pull'                         , 'pull'],
       \ 'r' : [':GRemove'                          , 'remove'],