Updated documentation with development notes

It took me a bit to figure out the correct make sequence, so I added a simple note about it.
I also added a new make target for simplicity sake.

Author: chrislovecnm

Makefile

@@ -96,6 +96,10 @@ generate_docs:
 generate:
 	@source test/make.sh && generate
 
+.PHONY: dev
+dev: generate generate_docs
+	@echo "Updated files"
+
 # Versioning
 .PHONY: version
 version:

README.md

@@ -233,6 +233,9 @@ To more cleanly handle cases where desired functionality would require complex d
 
 The root module is generated by running `make generate`. Changes to this repository should be made in the [`autogen`](/autogen) directory where appropriate.
 
+Note: The correct sequence to update the repo using autogen funcationality is the run `make generate && make generate_docs`.  This
+will create the various terraform files, and then generate the terraform documentation using `terraform-docs`.
+
 ## Testing
 
 ### Requirements