Update Question 11.6:

• Add X.Org installation from packages
• Add a paragraph about X.Org installation from sysinstall(8)
• Rewrite the paragraph about xorgcfg(1) to fit into the modified answer (suggested by trhodes)
• Remove last paragraph about Xi Graphics since they have no FreeBSD support anymore

Reviewed by: trhodes, danger
Approved by: gabor