Free 't' for next alias

Use 'r' for typos since it's typo of 't'.

dotfiles/gittum/main.gitconfig

   cma = commit --verbose --amend
   cmf = !sh -c \
         'git commit --edit --message=\"$(~/.gittum/bin/findcat msg_flake8)\"'
-  cmt = !sh -c \
+  cmr = !sh -c \
         'git commit --edit --message=\"$(~/.gittum/bin/findcat msg_typo)\"'
   cmv = !sh -c \
         'git commit --verbose --edit --message=\"$(~/.gittum/bin/findcat msg_bumpv)\"'