Add man page for chef-server-ctl.

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```
$ man chef-server-ctl
CHEF-SERVER-CTL(8)                                                              knife                                                             CHEF-SERVER-CTL(8)

NAME
       chef-server-ctl - The man page for the chef-server-ctl command line tool.

       The  Chef server includes a command-line utility named chef-server-ctl. This command-line tool is used to start and stop individual services, reconfigure the
       Chef server, run chef-pedant, and then tail Chef server log files.

BACKUP-RECOVER
       The backup-recover subcommand is used to force the Chef server to attempt to become the backup server. This is the opposite of the master-recover subcommand.

       WARNING:
          If this command is run on both back-end servers, it will put the back-end cluster into a state where no server holds the DRBD resource.

       This subcommand has the following syntax:

          $ chef-server-ctl backup-recover

CLEANSE
       The cleanse subcommand is used to re-set the Chef server to the state it was in before the first time the reconfigure subcommand is run to destroy all  data,
       configuration files, and logs.

       This subcommand has the following syntax:

          $ chef-server-ctl cleanse

GATHER-LOGS
       The gather-logs subcommand is used to gather the Chef server log files into a tarball that contains all of the important log files and system information.

       This subcommand has the following syntax:

          $ chef-server-ctl gather-logs
...
```