Update homebrew release docs.

`brew bump-formula-pr` has simplified the process for updating brew
forumla

docs/development/homebrew.md

@@ -4,13 +4,20 @@ Submitting a new release of kops to Homebrew is very simple.
 
 ### From a homebrew machine
 
-```brew edit kops``` will open an editor on your machine to edit the formula. Make the following changes:
+`brew bump-formula-pr` makes it easy to update our homebrew formula.  This will automatically update the provided fields and open a PR for you.  More details on this script are located [here.](https://github.com/Homebrew/brew/blob/master/Library/Homebrew/dev-cmd/bump-formula-pr.rb)
+
+Example usage:
+```
+brew bump-formula-pr --url=https://github.com/kubernetes/kops/archive/1.7.1.tar.gz --sha256=044c5c7a737ed3acf53517e64bb27d3da8f7517d2914df89efeeaf84bc8a722a
+```
 
 * Update the URL variable to the tar.gz of the new release source code
 * Update the sha256 variable to SHA256 checksum of the new tar.gz
 
 **If we change how dependencies work or if we make the install require something other than a simple make, we'll need to update the commands**
 
+```brew edit kops``` will open an editor on your machine to edit the formula. You can use this to make more in depth changes to the formula.
+
 ### Test that Homebrew formula works
 ```brew uninstall kops && brew install kops``` will install the new version. Test and make sure that the new release works.