texlive: Add a link for TEXLIVE_REV information.

Avoids chicken and egg problem where you don't have files in WRKSRC
before you know what the source archive tarball is called.  Ideally this
should be its own target that parses the URL directly and shows the
correct revision for the package in question, but I'll leave that for
those who understand this infrastructure better.

Author: jperkin

print/texlive/package.mk

@@ -1,4 +1,4 @@
-# $NetBSD: package.mk,v 1.27 2020/05/08 02:58:03 markd Exp $
+# $NetBSD: package.mk,v 1.28 2025/12/04 11:40:48 jperkin Exp $
 #
 # This Makefile fragment is intended to be included by packages that build
 # TeX Live packages.
@@ -23,7 +23,8 @@
 #	packages do not have a revision number in the DISTNAME).
 #	To obtain information to be used as TEXLIVE_REV you should use the
 #	value of "revision" line usually available in
-#	${WRKSRC}/tlpkg/tlpobj/${DISTNAME}.tlpobj
+#	${WRKSRC}/tlpkg/tlpobj/${DISTNAME}.tlpobj, or
+#	https://mirrors.ctan.org/systems/texlive/tlnet/tlpkg/texlive.tlpdb
 #
 # TEXLIVE_UNVERSIONED
 #	The distfile is an oldstyle unversioned one, normally