port-macppc/45186: install quirk documentation

[ozone%cname.com@localhost]

>Number:         45186
>Category:       port-macppc
>Synopsis:       install quirk documentation
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    port-macppc-maintainer
>State:          open
>Class:          doc-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Jul 28 01:10:00 +0000 2011
>Originator:     ozone
>Release:        5.1
>Organization:
volcano wireless
>Environment:
na
>Description:
INSTALL documents should have a Quirks section.

For macppc, references to PR 44896 and this mail from the archives:

http://mail-index.netbsd.org/port-macppc/2009/03/02/msg000617.html

would have been *extremely* helpful when I stumbled into this 
known-but-not-well-documented trap with auto-boot.

>How-To-Repeat:
Follow the regular INSTALL for NetBSD/macppc on a G4 Mini.

>Fix:
Steinlager is on sale at my local 7-11.