Comment 2 for bug 1650795

This is a documentation bug / a bug with a comment.

~~~
# Swift hash suffix. If left unset, one will be automatically
# generated. (string value)
undercloud_swift_hash_suffix = <None>
~~~

>> "This is not a bug. <None> is not a valid string value. If you un-comment the parameter, you need to give a value like IXQUPsHD1oe9KQJx for example."
Yep. But the comment is not saying this. Instead, a user who accidentally removes the comment gets a cryptographic error message somewhere down the road. I'm not asking to fix anything in the code. I'm only asking to change the comment to something more verbose, e.g. introducing
~~~
# The value needs to be alphanumeric. Setting this to <None> will lead to a deployment error.
~~~

For me a bug or documentation bug is when a customer opens a support ticket and I need to troubleshoot it, and when this could have been avoided either by a better error message or a better documentation / comment in the file.