add a more specific reference

Author: tbrowder

doc/Language/modules.pod6

@@ -662,9 +662,10 @@ C<TODO>, or other files.>
 
 If your module requires extra processing during installation to fully
 integrate with and use non-Perl operating system resources, you may
-need to add a C<Build.pm6> file to the top-level directory. It will
+need to add a C<Build.pm6> file (a "build hook") to the top-level directory. It will
 bu used by the C<zef> installer as the first step in the installation process.
-See various usage scenarios in existing ecosystem modules such as C<zef> itself.
+See the README for C<zef> for a brief example. Also see various usage scenarios in existing
+ecosystem modules such as C<zef> itself.
 =end item
 
 =begin item