git: alias diff-last

setup

@@ -16,4 +16,5 @@ git config --global diff.tool vimdiff
 
 # aliases
 git config --global alias.branches "branch --all"
+git config --global alias.diff-last "diff HEAD^ HEAD"
 git config --global alias.tree "log --graph --abbrev-commit --decorate --format=format:'%C(red)%h%C(reset)%C(bold red)%d%C(reset) %C(dim green)(%ar)%C(reset) %C(bold black)%s%C(reset) %C(dim white)(%an)%C(reset)' --all"