change `git submodule` aliases to use `gsm` just in case

`gs` already pulling double duty as `git status` and `git show`, so should try
to make it potentially less confusing.

zsh/omz-custom/git.zsh

@@ -32,8 +32,8 @@ alias gsr='git show --format=raw'
 
 # useful if you forget to setup tracking for a new branch when checking out.
 alias track='git branch --set-upstream $(current_branch) origin/$(current_branch) && git fetch'
-alias gsu='git submodule sync && git submodule update --init'
-alias gsp='git submodule foreach git pull origin master'
+alias gsmu='git submodule sync && git submodule update --init'
+alias gsmp='git submodule foreach git pull origin master'
 
 # useful omz git plugin ones include:
 #   ga, gc, gco, gb, gba, gm, grhh, ggpull, ggpush