Fix issues noted by igor/manlint

• Fix typos [1]:
  • manged -> managed
  • specifiying -> specifying
• Escape '.' at start of lines using & to tell the roff processor that the line isn't meant to be treated as a command [2].

Bump .Dd for the change

MFC after: 1 week
Reported by: igor [1], manlint [2]
Sponsored by: Dell EMC Isilon