DOC: reverse order of release notes, so most recent ones are first

Author: rgommers

doc/source/releasenotes.rst

@@ -4,20 +4,20 @@ Release Notes
 .. toctree::
    :maxdepth: 1
 
-   release.0.3.0
-   release.0.4.0
-   release.0.5.0
-   release.0.5.1
-   release.0.5.2
+   release.1.6.0
+   release.1.5.0
+   release.1.4.1
+   release.1.4.0
+   release.1.3.0
+   release.1.2.0
+   release.1.1.1
    release.1.0.0
-   release.1.0.1
-   release.1.0.2
    release.1.0.3
+   release.1.0.2
+   release.1.0.1
    release.1.1.0
-   release.1.1.1
-   release.1.2.0
-   release.1.3.0
-   release.1.4.0
-   release.1.4.1
-   release.1.5.0
-   release.1.6.0
+   release.0.5.2
+   release.0.5.1
+   release.0.5.0
+   release.0.4.0
+   release.0.3.0