Add placeholder 15.5 release notes
Add placeholder 15.5 release notes

Not done, but we can add to this.

Signed-off-by: Tim Smith <764ef62106582a09ed09dfa0b6bff7c05fd7d1e4@chef.io>

nvwls/chef,tas50/chef-1,jaymzh/chef,mattray/chef,tas50/chef-1,chef/chef,MsysTechnologiesllc/chef,jaymzh/chef,nvwls/chef,mattray/chef,jaymzh/chef,mwrock/chef,chef/chef,jaymzh/chef,nvwls/chef,tas50/chef-1,higanworks/chef,higanworks/chef,higanworks/chef,nvwls/chef,gene1wood/chef,higanworks/chef,MsysTechnologiesllc/chef,MsysTechnologiesllc/chef,tas50/chef-1,mattray/chef,chef/chef,chef/chef,mattray/chef,higanworks/chef,nvwls/chef,mattray/chef,nvwls/chef,mwrock/chef,gene1wood/chef,mwrock/chef,mwrock/chef,gene1wood/chef,MsysTechnologiesllc/chef,gene1wood/chef