docs(@angular/cli): add cherry-pick instructions.
docs(@angular/cli): add cherry-pick instructions.

This includes instructions on how to cherry-pick commits into the patch branch. Since `cherry-pick` isn't that commonly used, it's useful to write this down for developers who might not be that familiar with it. It also includes fetching the commit beforehand, so users don't get "bad object" errors which can be annoying to work around.

The `-x` option is used as well to include a reference to the commit the cherry-pick came from.

beeman/angular-cli,beeman/angular-cli,geofffilippi/angular-cli,catull/angular-cli,DevIntent/angular-cli,catull/angular-cli,filipesilva/angular-cli,ocombe/angular-cli,angular/angular-cli,catull/angular-cli,clydin/angular-cli,ocombe/angular-cli,filipesilva/angular-cli,ocombe/angular-cli,manekinekko/angular-cli,DevIntent/angular-cli,DevIntent/angular-cli,angular/angular-cli,DevIntent/angular-cli,Brocco/angular-cli,hansl/angular-cli,angular/angular-cli,geofffilippi/angular-cli,clydin/angular-cli,geofffilippi/angular-cli,Brocco/angular-cli,ocombe/angular-cli,hansl/angular-cli,beeman/angular-cli,angular/angular-cli,hansl/angular-cli,clydin/angular-cli,Brocco/angular-cli,manekinekko/angular-cli,hansl/angular-cli,beeman/angular-cli,filipesilva/angular-cli,filipesilva/angular-cli,DevIntent/angular-cli,catull/angular-cli,ocombe/angular-cli,manekinekko/angular-cli,Brocco/angular-cli,Brocco/angular-cli,clydin/angular-cli,geofffilippi/angular-cli