git:spull: Rename to ssync

As I rarely use git-pull(1) and instead fetch and act manually, I'd
rather have it to just sync the submodules.

.config/zsh/autoload/git/git-ssync

@@ -0,0 +1,6 @@
+#!/usr/bin/env zsh
+
+emulate -L zsh -o err_return
+
+git submodule sync --recursive
+git submodule update --init --recursive