Add 'make help', and add brief build documentation

Author: i80and

Makefile

@@ -1,9 +1,12 @@
 GIT_BRANCH=`git rev-parse --abbrev-ref HEAD`
 
-.PHONY: all serve
+.PHONY: all serve help
 
-all:
+help: ## Show this help message
+	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-20s\033[0m %s\n", $$1, $$2}'
+
+all: ## Build the documentation under build/<git branch>
 	hugo -d build/$(GIT_BRANCH)
 
-serve:
+serve: ## Host the documentation on port 1313
 	hugo serve

README.md

@@ -8,3 +8,7 @@ Style Guide](https://docs.mongodb.com/manual/meta/style-guide/).
 ## Installation Instructions
 
     brew install hugo mmark
+
+## Building Instructions
+
+    make