Revert "Give Zef some more prominence."

This reverts commit b952596.

zef doesn't properly install Inline::Perl5 and probably other dists
that compile native libraries during their build. So pull back on
the publicity until this is fixed.

includes/footer

@@ -34,8 +34,6 @@
               directory</a></li>
           <li><a href="https://github.com/tadzik/panda/">Panda</a>, a
           module installer for Rakudo</li>
-          <li><a href="https://github.com/ugexe/zef/">Zef</a>, a young
-          and feature rich module installer</li>
         </ul>
 
         <a href="https://modules.perl6.org/" class="btn btn-success">More</a>

source/downloads/index.html

@@ -32,7 +32,7 @@ <h3 class="trim-top">Installing from source</h3>
         <pre>git clone https://github.com/tadzik/rakudobrew ~/.rakudobrew
 export PATH=~/.rakudobrew/bin:$PATH
 rakudobrew build moar 2015.12
-rakudobrew build panda # alternative: build zef</pre>
+rakudobrew build panda</pre>
 
         <p>Note: if you have old installation of <code>rakudobrew</code> or Perl 6 and you're having issues updating,
         you may try deleting <code>~/.rakudobrew</code> and <code>~/.perl6</code> directories first and starting
@@ -68,10 +68,7 @@ <h3 class="trim-top">Perl&nbsp;6 Ecosystem</h3>
           <a href="https://modules.perl6.org/">Modules extending Perl&nbsp;6</a>
         </p>
         <p>
-          <a href="https://github.com/tadzik/panda">Panda Module installer</a>
-        </p>
-        <p>
-          <a href="https://github.com/ugexe/zef">Zef Module installer</a>
+          <a href="https://github.com/tadzik/panda">Module installer</a>
         </p>
       </div>
     </div>

source/whatever/index.html

@@ -22,10 +22,8 @@ <h3 class="panel-title">Installer, Editors, IDEs, *</h3>
       </div>
       <div class="panel-body">
         <ul class="shy-list">
-            <li><a href="https://github.com/tadzik/panda/">Panda</a> makes it easy
+            <li><a href="https://github.com/tadzik/panda/">panda</a> makes it easy
             to install modules programs written in Perl&nbsp;6</li>
-            <li><a href="https://github.com/ugexe/zef/">Zef</a>, a young
-            and feature rich module installer</li>
             <li><a href="https://metacpan.org/pod/Inline::Perl6">Inline::Perl6</a>, embedding Perl&nbsp;6 code in Perl&nbsp;5</li>
             <li><a href="https://metacpan.org/pod/Padre::Plugin::Perl6">Padre::Plugin::Perl6</a>, Perl&nbsp;6 highlighting and code execution in
                 <a href="http://padre.perlide.org/">Padre, the Perl IDE</a></li>