doc: update metacpan.org links to avoid redirects

The /release/ links are redirected to /dist/ and /pod/release/ to
/release/../view/, so update our links accordingly to avoid 301
redirects.

Discussion: https://postgr.es/m/CA672723-BAD2-436E-B6E6-163841E11A1B@yesql.se

doc/src/sgml/external-projects.sgml

@@ -65,7 +65,7 @@
       <entry>DBD::Pg</entry>
       <entry>Perl</entry>
       <entry>Perl DBI driver</entry>
-      <entry><ulink url="https://metacpan.org/release/DBD-Pg"></ulink></entry>
+      <entry><ulink url="https://metacpan.org/dist/DBD-Pg"></ulink></entry>
      </row>
 
      <row>

doc/src/sgml/install-windows.sgml

@@ -488,7 +488,7 @@ $ENV{CONFIG}="Debug";
       ActiveState Perl installation, nor in the ActiveState Perl Package
       Manager (PPM) library. To install, download the
       <filename>IPC-Run-&lt;version&gt;.tar.gz</filename> source archive from CPAN,
-      at <ulink url="https://metacpan.org/release/IPC-Run"></ulink>, and
+      at <ulink url="https://metacpan.org/dist/IPC-Run"></ulink>, and
       uncompress. Edit the <filename>buildenv.pl</filename> file, and add a PERL5LIB
       variable to point to the <filename>lib</filename> subdirectory from the
       extracted archive. For example:

src/test/perl/PostgreSQL/Test/Cluster.pm

@@ -1826,7 +1826,7 @@ sub psql
 	# and set the flag.  Otherwise, and for any other exception, rethrow.
 	#
 	# For background, see
-	# https://metacpan.org/pod/release/ETHER/Try-Tiny-0.24/lib/Try/Tiny.pm
+	# https://metacpan.org/release/ETHER/Try-Tiny-0.24/view/lib/Try/Tiny.pm
 	do
 	{
 		local $@;

src/tools/perlcheck/perlcriticrc

@@ -13,7 +13,7 @@ theme = core
 # print the policy name as well as the normal output
 verbose = %f: %m at line %l, column %c.  %e.  ([%p] Severity: %s)\n
 
-# Note: for policy descriptions see https://metacpan.org/release/Perl-Critic
+# Note: for policy descriptions see https://metacpan.org/dist/Perl-Critic
 
 
 # allow octal constants with leading zeros