Start ChefDK 3.7 release notes
Start ChefDK 3.7 release notes

Add a note about the deprecation in #1925

Signed-off-by: Bryan McLellan <9da9e2973b9c72b95f1bc7169993146760fceeb1@loftninjas.org>

chef/chef-dk,chef/chef-dk,chef/chef-dk