Update Question 10.18:

• Rewrite "lots of" as "lot of" (suggested by trhodes)
• Mark up telnet, ssh, screen with <command>
• Fix broken paragraphs (suggested by gabor)
• Remove MAKEDEV(8) method
• Update "pseudo-device" kernel option to "device"
• Generalize answer
• Note users have 256 ptys beginning from FreeBSD 6.3 and they can create 256 more

Reviewed by: trhodes, danger
Approved by: gabor