[doc] refactors guides index so the toc is showing up correctly in sidebar.

docs/guide/ext/docker.rst

@@ -1,5 +1,5 @@
-Bonobo with Docker
-==================
+Docker Extension
+================
 
 .. todo:: The `bonobo-docker` package is at a very alpha stage, and things will change. This section is here to give a
     brief overview but is neither complete nor definitive.

docs/guide/ext/jupyter.rst

@@ -1,5 +1,5 @@
-Bonobo with Jupyter
-===================
+Jupyter Extension
+=================
 
 There is a builtin plugin that integrates (somewhat minimallistically, for now) bonobo within jupyter notebooks, so
 you can read the execution status of a graph within a nice (ok, not so nice) html/javascript widget.

docs/guide/ext/selenium.rst

@@ -1,5 +1,5 @@
-Bonobo with Selenium
-====================
+Selenium Extension
+==================
 
 .. todo:: The `bonobo-selenium` package is at a very alpha stage, and things will change. This section is here to give a
           brief overview but is neither complete nor definitive.

docs/guide/ext/sqlalchemy.rst

@@ -1,5 +1,5 @@
-Bonobo with SQLAlchemy
-======================
+SQLAlchemy Extension
+====================
 
 .. todo:: The `bonobo-sqlalchemy` package is at a very alpha stage, and things will change. This section is here to
           give a brief overview but is neither complete nor definitive.