source/install.rst: put Debian version under the same subsection
diff --git a/doc/source/install.rst b/doc/source/install.rst
index c3fc04e..430990f 100644
--- a/doc/source/install.rst
+++ b/doc/source/install.rst
@@ -44,8 +44,10 @@
ostree bubblewrap python-ruamel-yaml
-Debian Stretch
-++++++++++++++
+Debian
+++++++
+Stretch
+^^^^^^^
With stretch, you first need to ensure that you have the backports repository
setup as described `here <https://backports.debian.org/Instructions/>`_
@@ -66,8 +68,8 @@
gir1.2-ostree-1.0 ostree
-Debian Buster or Sid
-++++++++++++++++++++
+Buster or Sid
+^^^^^^^^^^^^^
For debian unstable or testing, only the following line should be enough
to get the base system requirements installed::
