DOC: Update the upgrade procedure

Update the FreeIPA upgrade procedure as it was previously outdated.

https://fedorahosted.org/freeipa/ticket/2918

Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>
Document permanent lockout option

Document that setting the Lockout Duration to zero (0) will permanently
lockout an account after the number of failed attempts is reached.

https://fedorahosted.org/freeipa/ticket/4065

Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>
Installing.xml - essay consistency

Update the documentation to reflect that there are now only two ways
that the CA is incorporated.

https://fedorahosted.org/freeipa/ticket/4144

Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>