docs: remove git snapshot download links

The process used to build the snapshots no longer works because the box
it runs on is outdated. Analysing the web logs shows the majority of
traffic to these links is from search engine bots. With those removed,
there is about 1 hit per day from (probable) humans.

Most users needing a tarball are better served by using official
releases. Those needing latest code are better served by using git
checkout. The tarball snapshots are not compelling enough to invest time
in fixing the script that produces them.
Reviewed-by: NAndrea Bolognani <abologna@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

docs/downloads.html.in

@@ -433,21 +433,6 @@
       <li><a href="https://libvirt.org/sources/">libvirt.org HTTPS server</a></li>
     </ul>
 
-    <h2><a id="hourly">Hourly development snapshots</a></h2>
-
-    <p>
-      Once an hour, an automated snapshot is made from the git server
-      source tree. These snapshots should be usable, but we make no guarantees
-      about their stability; furthermore, they should NOT be
-      considered formal releases, and they may have transient security
-      problems that will not be assigned a CVE.
-    </p>
-
-    <ul>
-      <li><a href="ftp://libvirt.org/libvirt/libvirt-git-snapshot.tar.xz">libvirt.org FTP server</a></li>
-      <li><a href="https://libvirt.org/sources/libvirt-git-snapshot.tar.xz">libvirt.org HTTP server</a></li>
-    </ul>
-
     <h2><a id="schedule">Primary release schedule</a></h2>
 
     <p>