Add Git aliases for update-index & --skip-worktree

.gitconfig

@@ -46,13 +46,23 @@
 	# Unstage from the the staging area
 	unstage = reset HEAD
 
-	# Mark a file as "assume unchanged"
+	# Git `update-index` shorthand
+	ui = update-index
+
+	# Mark a file as "assume unchanged": good for perf
 	assume = update-index --assume-unchanged
 	# Reverse the above
 	unassume = update-index --no-assume-unchanged
 	# Show the files that are currently assume-unchanged
 	assumed = !git ls-files -v | grep ^h | cut -c 3-
 
+	# Mark a file as "skip worktree": good for config files
+	skip = update-index --skip-worktree
+	# Reverse the above
+	unskip = update-index --no-skip-worktree
+	# Show the files that are currently skip-worktree'd
+	skipped = !git ls-files -v | grep ^S | cut -c 3-
+
 	# Create an annotated tag with a message for a (sem)ver release
 	ver = "!f() { git tag -a ${1} -m \"${1}\"; }; f"
 
@@ -64,7 +74,7 @@
 
 	# Show verbose output about tags, branches or remotes
 	tags = tag -l
-	branches = branch -a # -v for verbose
+	branches = branch -a
 	remotes = remote -v
 
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