Add docs target to Makefile

Author: skimbrel

Makefile

@@ -14,3 +14,9 @@ clean:
 authors:
 	echo "Authors\n=======\n\nA huge thanks to all of our contributors:\n\n" > AUTHORS.md
 	git log --raw | grep "^Author: " | cut -d ' ' -f2- | cut -d '<' -f1 | sed 's/^/- /' | sort | uniq >> AUTHORS.md
+
+docs:
+	mvn javadoc:javadoc
+	@echo "If you want to update the Github Pages site:\n"
+	@echo "git checkout -b gh-pages origin/gh-pages; cp -r target/apidocs/* ."
+	@echo "\nReview, commit (but don't add target/), then push."