Fix typo in 0.5.1 release notes

max_tries is the name in the C source, max-tries is the argument to the module.

Now this might seem relatively innocuous, but somewhere down the line pam-auth-update ended up setting max_tries=1, which means a lot of systems out there might be using the default (3 for now) instead of the 1 expected.

Of course that pam-auth-update typo may not have been caused by this one