DOC: organize TOC

Author: jklymak

doc/users/index.rst

@@ -7,18 +7,37 @@
 Users guide
 ###########
 
+
+General
+#######
+
 .. toctree::
    :maxdepth: 2
 
-   installing/index.rst
-   ../plot_types/index.rst
-   ../tutorials/index.rst
-   ../gallery/index.rst
    getting_started/index.rst
+   installing/index.rst
    explain/index.rst
    faq/index.rst
-   ../api/index.rst
    resources/index.rst
+
+Reference 
+#########
+
+.. toctree::
+   :maxdepth: 2
+
+   ../api/index.rst
    ../devel/index.rst
    backmatter/index.rst
    release_notes.rst
+
+
+Tutorials and examples
+######################
+
+.. toctree::
+   :maxdepth: 1
+
+   ../plot_types/index.rst
+   ../tutorials/index.rst
+   ../gallery/index.rst