#1194 Add Package Dependency Update to Cleanup Instructions

Originally at 2015-06-15T19:26:07Z by Sean DeNigris closed at 2015-06-15T19:30:48Z `amber init` automatically adds Web and Silk to the main package. uninstall.html doesn't mention this, and so following the instructions exactly leads to an error when you run `grunt devel` after uninstalling e.g. Silk.