Add 7.0.3 release landing page

R1/source/releases/rel7.0.3.rst

+.. _rel7.0.3:
+
+Varnish Cache 7.0.3
+===================
+
+* Source download `varnish-7.0.3.tgz </downloads/varnish-7.0.3.tgz>` not yet _
+
+* SHA256=<sha checksum here>
+
+Varnish Cache 7.0.3 is a security fix of 7.0, related to
+:ref:`VSV00009`. All users should, as soon as possible, upgrade to a
+secure version, either 7.0.3 or 7.1.1.
+
+More information:
+
+* `Changelog entry for 7.0.3 <https://github.com/varnishcache/varnish-cache/blob/7.0/doc/changes.rst#varnish-cache-703-2022-08-09>`_
+
+* List of most important `Changes in 7.0 <https://varnish-cache.org/docs/7.0/whats-new/changes-7.0.html>`_
+
+* Help on `Upgrading to Varnish 7.0 <https://varnish-cache.org/docs/7.0/whats-new/upgrading-7.0.html>`_
+
+For installation instructions including information about cloud images see
+`the Varnish Installation Manual </docs/trunk/installation/index.html>`_
+
+We recommend using the manual installation procedure available at:
+https://packagecloud.io/varnishcache/varnish70/install#manual