In kdb5_util.rst, reorder the main option summary to match the order
they are documented in below, and document the -x option. Remove the
kdb5_util create -h switch case as 'h' has never been in the getopt
string. Add the -r18 option to the kdb5_util dump and load option
summaries. Reword the kdb5_util load -hash option. Remove the
nonexistent kdb5_util load dbname parameter.
In database.rst, alter the example for loading a single principal to
use the dump principal filtering functionality, as that functionality
does not currently exist for load.
In the kdb5_util usage error message, reorder the main options to
match the order in the documentation and to fit within 79 columns.
Also add the -P option.
(cherry picked from commit fa000575085be71bfc326221a4d4d23fc00a1462)