mk/help: document PREPEND_PATH


(rillig)

# $NetBSD: path.help,v 1.1 2018/11/11 20:38:27 rillig Exp $

# Package-settable variables:
#
# PREPEND_PATH
#	A space-separated list of path names. All directories that are
#	added to this list are added to the PATH environment variable,
#	in reverse order. To add a directory at the very front of the
#	PATH, append to this variable after including bsd.prefs.mk and
#	right before including bsd.pkg.mk.
#
#	The modified PATH is available in all {pre,do,post}-* targets,
#	as well as the configure scripts and invocations of the make
#	targets in the package itself.
#
# Keywords: PATH