Add graphicsmagick versioned feature

README.md

@@ -46,14 +46,15 @@ Each of the following parts represents another feature and version. Available
 options are:
 
 1. `golang`
-2. `git`
-3. `chrome`
-4. `node`
-5. `yarn`
-6. `phantomjs`
-7. `postgres`
-8. `terraform`
-9. `ansible`
+1. `git`
+1. `chrome`
+1. `node`
+1. `yarn`
+1. `phantomjs`
+1. `postgres`
+1. `terraform`
+1. `ansible`
+1. `graphicsmagick`
 
 ### Adding a new build