Update to r42903:

This patch does the following to the first half of 5.6. Using the Ports Collection:

• removes csup warnings and how-tos
• remove Method 3 as sysinstall is being phased out
• adds some text and word-smithing to make unclear instructions a bit clearer
• some tag cleanup
• updated lsof listing
• some text shuffling to improve flow

Reviewed by: bcr
Differential Revision: https://reviews.freebsd.org/D5464