add README

README.md

@@ -1,10 +1,34 @@
-# Hello Build Pack
+Heroku buildpack: Hello
+=======================
 
-The Hello Build Pack will look for a file named `hello.txt` in the app root and
-display its contents during push.
+This is an example [Heroku buildpack](#).
 
-## Usage
+Usage
+-----
 
-Add this language pack to your `BUILDPACK_URL`.
+Example usage:
 
-    heroku config:add BUILDPACK_URL="http://github.com/heroku/heroku-buildpack-hello.git"
+    $ ls
+    hello.txt
+
+    $ heroku create --stack cedar --buildpack http://github.com/heroku/heroku-buildpack-hello.git
+
+    $ git push heroku master
+    ...
+    -----> Heroku receiving push
+    -----> Fetching custom buildpack
+    -----> HelloFramework app detected
+    -----> Found a hello.txt
+
+The buildpack will detect that your app has a `hello.txt` in the root. If this file has contents, it will be copied to `goodbye.txt` with instances of the world `hello` changed to `goodbye`.
+
+Hacking
+-------
+
+To use this buildpack, fork it on Github.  Push up changes to your fork, then create a test app with `--buildpack <your-github-url>` and push to it.
+
+For example, you can change the displayed name of the buildpack to `GoodbyeFramework`. Open `bin/detect` in your editor, and change `HelloFramework` to `GoodbyeFramework`.
+
+Commit and push the changes to your buildpack to your Github fork, then push your sample app to Heroku to test.  You should see:
+
+    -----> GoodbyeFramework app detected