Add `update` make task

Also bump Riot and Skeleton versions. HighlightJS seems too hard to have
in the `update` task, as we have a customised version containing only
bash and markdown.

Also fix makefile throwing an `rm` error when dist does not exist.

Makefile

@@ -5,11 +5,11 @@
 
 # Auto-Documenting Section. Displays a target list with `##` descriptions.
 help:
-	@grep -E '^[a-zA-Z_-]+:.*## .*$$' $(MAKEFILE_LIST) | awk 'BEGIN {FS = ":.*?## "}; {printf "%-15s %s\n", $$1, $$2}'
+	@grep -E '^[a-zA-Z_-]+:.*## .*$$' $(MAKEFILE_LIST) | awk 'BEGIN {FS = ":.*?## "}; {printf "* %-10s %s\n", $$1, $$2}'
 
-dist: ## Create a distribution for live usage
+dist: ## Create a distribution for live usage.
 	# --- Create Folders ---
-	@rm -r dist/*
+	@rm -rf dist/*
 	@mkdir -p dist/css dist/js dist/tags
 	# --- Combine CSS ---
 	@for file in $$(cat css/app.css | sed "$(CSS_FILES)"); do \
@@ -41,3 +41,11 @@ APPJS_PH = <!-- appjsplaceholder -->
 APPJS_TAG = <script type='text/javascript' src='js/app.js'></script>
 APPTAG_PH = <!-- apptagplaceholder -->
 APPTAG_TAG = <script type='riot/tag' src='tags/app.tag'></script>
+
+update: ## Get latest js/css library versions.
+	# -- Update Riot --
+	@curl https://raw.githubusercontent.com/riot/riot/master/riot+compiler.min.js \
+	  -o js/vendor/riot+compiler.min.js -#
+	# -- Update Skeleton --
+	@curl https://raw.githubusercontent.com/skeleton-framework/skeleton-framework/master/dist/skeleton.min.css \
+	  -o css/vendor/skeleton.min.css -#