Add info about user-env-compile and pipeline.

Author: timshadel

README.md

@@ -1,12 +1,16 @@
 Heroku buildpack: Github private repo access via ~/.netrc
 ===================================
 
-This buildpack uses a Github OAuth2 token exposed as `GITHUB_BASIC_TOKEN`
+This buildpack uses a Github OAuth2 token exposed as `GITHUB_AUTH_TOKEN`
 to resolve private repository URLs without putting a specific username
 or password in the URLs saved in local files (e.g. `package.json`).
 
 See [Easier builds and deployments using Git over HTTPS and
-OAuth][github-builds] and [Github OAuth — Non-web Application Flow][github-oauth] for more detail. Also, you may want to choose a user with read-only access 
+OAuth][github-builds] and [Github OAuth — Non-web Application Flow][github-oauth] for more detail. Also, you may want to choose a user with read-only access.
+
+If you use this in conjunction with the `labs:pipeline` feature of Heroku, you may
+avoid setting the `GITHUB_AUTH_TOKEN` environment variable on your test & prod apps,
+and instead only set it on the app where you push your code & which runs the buildpack.
 
 [github-builds]: https://github.com/blog/1270-easier-builds-and-deployments-using-git-over-https-and-oauth
 
@@ -17,7 +21,10 @@ Example usage:
 
     $ heroku create --stack cedar --buildpack http://github.com/fs-webdev/heroku-buildpack-netrc.git
 
-    $ source
+    # Enable 
+    $ heroku labs:enable user-env-compile
+    $ heroku config:set GITHUB_AUTH_TOKEN=<my-read-only-token>
+
     $ git push heroku master
     ...
     -----> Heroku receiving push