Significantly improve the handling of --with-pmdir.

doc/HOWTO-RELEASE

@@ -7,14 +7,32 @@ How to make a new release of GNU Stow
 
   - Check CPAN distribution will work via Module::Build:
 
-      - Run ./configure && make to generate stow, chkstow, and lib/Stow.pm
+      - Generate stow, chkstow, and lib/Stow.pm via:
+
+          eval `perl -V:siteprefix`
+          ./configure --prefix=$siteprefix && make
+
         (N.B. the CPAN distribution will contain these files, whereas
         the GNU distribution will not.)
-      - Run perl Build.PL.
-      - Run ./Build test
-      - Run ./Build install
-      - Run ./Build distcheck
-      - Run ./Build distmeta and check META.* have the new version number.
+
+      - Make sure bin/stow does not contain a "use lib" line.  This
+        should only happen if the installation directory for Perl
+        modules (--with-pmdir's default value) is not in Perl's
+        built-in @INC, which would be caused by ./configure's default
+        prefix (/usr/local) not matching your Perl's siteprefix, but
+        the above --prefix should prevent that, as would:
+
+          ./configure --with-pmdir=`perl -le 'print $INC[0]'`
+
+      - Make sure all the following commands all run successfully:
+
+          perl Build.PL
+          ./Build test
+          ./Build install
+          ./Build distcheck
+          ./Build distmeta
+
+      - Check META.yaml and META.json have the new version number.
 
   - Ensure all changes are committed to git.