MFC 362491:

Improve the rcorder manual page

• Fix formatting issues such as:
  • Use Ql instead of Dq Li as Li is deprecated
  • Address some mandoc warnings
• Add arguments missing from the list of options (i.e., document "-k keep" instead of just "-k").
• Document that -k and -s can be specified multiple times
• Use sshd instead of named for the example in the BUGS section, as named is not in the base system. Also, use Nm instead of Xr there as it is not the sshd binary that is required to be running, but the service.
• Use Sy instead of Cm for KEYWORDS. Cm is reserved for command-line modifiers of the CLI.
• Add an EXAMPLES section
• Cross-reference service(8).