Cookbook - clean up deployment docs

Remove the head2 section that referred to Dancer2::Deployment that is
now part of the Cookbook.

Remove notes about setting prefix when mounting multiple apps (now we dispatch
on Request->dispatch_path ).
Update changes
Merge branch 'veryrusty-Pr/deployment_docs' into devel
Remove obsolete and experimental "auto_reload" from documentation and script/dancer2
Add the auto reloading with Plack and Shotgun recipe
Changes
Merge branch 'azawawi-devel' into devel