update README

Makefile

@@ -25,6 +25,9 @@ libucl: vendor/libucl/$(LIBUCL_NAME)
 test: libucl
 	go test $(TEST) $(TESTARGS)
 
+updatedeps:
+	go get -u -v ./...
+
 vendor/libucl/libucl.a: vendor/libucl
 	cd vendor/libucl && \
 		cmake cmake/ && \
@@ -44,4 +47,4 @@ vendor/libucl:
 clean:
 	rm -rf vendor
 
-.PHONY: clean default libucl test
+.PHONY: clean default libucl test updatedeps

README.md

@@ -6,3 +6,42 @@
 
 Terraform is a tool for building and changing infrastructure
 safetly and efficiently.
+
+## Developing Terraform
+
+If you wish to work on Terraform itself or any of its built-in providers,
+you'll first need [Go](http://www.golang.org) installed (version 1.2+ is
+_required_). Make sure Go is properly installed, including setting up
+a [GOPATH](http://golang.org/doc/code.html#GOPATH). Make sure Go is compiled
+with cgo support. You can verify this by running `go env` and checking that
+`CGOENABLED` is set to "1".
+
+Next, install [Git](http://git-scm.com/), which is needed for some dependencies.
+
+Finally, install [Gox](https://github.com/mitchellh/gox), which is used
+as a compilation tool on top of Go:
+
+    $ go get -u github.com/mitchellh/gox
+
+Next, clone this repository into `$GOPATH/src/github.com/hashicorp/terraform`
+and then just type `make`. This will compile some dependencies and then
+run the tests. If this exits with exit status 0, then everything is working!
+
+    $ make
+    ...
+
+To compile a development version of Terraform and the built-in plugins,
+run `make dev`. This will put Terraform binaries in the `bin` folder:
+
+    $ make dev
+    ...
+    $ bin/terraform
+    ...
+
+
+If you're developing a specific package, you can run tests for just that
+package by specifying the `TEST` variable. For example below, only
+`terraform` package tests will be run.
+
+    $ make test TEST=./terraform
+    ...