MFC r339990:

mount_smbfs(8): Add the STANDARDS and HISTORY sections

• Document that mount_smbfs(8) only supports SMB1 and that SMB2 and SMB3 are not supported at the moment. Suggest users to browse ports for software compatible with newer versions of the protocol.
• Copy supported servers list from README.
• Add a SEE ALSO section and reference the chapter about Samba in the FreeBSD Handbook.
• Add a HISTORY section.
• Style changes:
  • Use Dq instead of Em in the EXAMPLES section.
  • Mark command modifiers with Cm.

Reviewed by: bcr
Approved by: bcr (mentor)
Approved by: krion (mentor, implicit), mat (mentor, implicit)
Sponsored by: Bally Wulff Games & Entertainment GmbH
Differential Revision: https://reviews.freebsd.org/D17798