Fix unterminated alias in git/gitconfig-osx

[Alhadis]

As evidenced by its broken syntax highlighting, gitconfig-osx contains an unterminated shell command in one of its aliases:

dotfiles/git/gitconfig-osx

Lines 12 to 22 in 727f8f9

	# Change to working directory to the root of the git repo.
	#
	# @usage
	# git root
	#
	root = "!_() { !pwd -P }"
	#
	# Diffs the changes git stash would apply.
	#
	# @usage

This PR simply adds the missing semicolon needed to terminate the call to pwd(1):

[alias]
	# Change to working directory to the root of the git repo.
	#
	# @usage
	#   git root
	#
	root = "!_() { !pwd -P; }"

	# Renames the provided stash.
	# http://stackoverflow.com/a/25935360/256429