Add RPM install instructions to INSTALL.rst.

INSTALL.rst

 INSTALLATION
 ============
 
+RPMs
+~~~~
+
+Binary, debuginfo and source RPMs for the VMOD are available at:
+
+	https://pkg.uplex.de/
+
+The packages are built for Enterprise Linux 7 (el7), and hence will
+run on compatible distros (such as RHEL7, Fedora, CentOS 7 and Amazon
+Linux).
+
+To add the repo to your YUM configuration::
+
+  yum-config-manager --add-repo https://pkg.uplex.de/rpm/7/uplex-varnish/x86_64/
+
+The RPM for the VMOD requires a Varnish installation from the official
+packages:
+
+	https://packagecloud.io/varnishcache
+
+You can then install the VMOD with::
+
+  yum install vmod-selector
+
+If you have problems or questions concerning the RPMs, post an issue
+to the source repository web site for the VMOD, or contact
+<varnish-support@uplex.de>.
+
+Building from source
+~~~~~~~~~~~~~~~~~~~~
+
 The VMOD is built against a Varnish installation, and the autotools
 use ``pkg-config(1)`` to locate the necessary header files and other
 resources. This sequence will install the VMOD::