abuild: include MAINTAINER in default abuild.conf

For the sake of completeness, include MAINTAINER as well as
PACKAGER to provide newapkbuild with comment metadata.

abuild.conf

@@ -24,8 +24,10 @@ SRCDEST=/var/cache/distfiles
 # where $repo is the name of the parent directory of $startdir.
 REPODEST=$HOME/packages/
 
-# PACKAGER is used to create new aports with 'newapkbuild ...'
+# PACKAGER and MAINTAINER are used by newapkbuild when creating new aports for
+# the APKBUILD's "Contributor:" and "Maintainer:" comments, respectively.
 #PACKAGER="Your Name <your@email.address>"
+#MAINTAINER="$PACKAGER"
 
 # what to clean up after a successful build
 CLEANUP="srcdir pkgdir deps"