Created Release Notes chapter

Co-Authored-By: Patrick Petit <ppetit@mirantis.com>
Co-Authored-By: Simon Pasquier <spasquier@mirantis.com>
Change-Id: I64137f25b7411cc6aa7bab199341beaae4e3c796

doc/source/index.rst

@@ -9,7 +9,7 @@ User documentation
    :maxdepth: 2
 
    overview
-   news
+   releases
    installation
    user
    licenses

doc/source/news.rst

@@ -1,6 +0,0 @@
-.. _news:
-
-What's new in 0.8
-=================
-
-TBD

doc/source/releases.rst

@@ -0,0 +1,20 @@
+.. _releases:
+
+Release Notes
+=============
+
+Version 0.8.0
+-------------
+
+- Add support for the "influxdb_grafana" Fuel Plugin role instead of
+  the "base-os" role which had several limitations.
+- Add support for retention policy configuration.
+- Upgrade to InfluxDB 0.9.4 which brings metrics time-series with tagging.
+- Upgrade to Grafana 2.5.0.
+- Several dashboard visualisation improvements.
+- A new self-monitoring dashboard.
+
+Version 0.7.0
+-------------
+
+- Initial release of the plugin. This is a beta version.