Add more information for unmanaged extensions

docs/extension.rst

@@ -365,10 +365,12 @@ stores. This is a typical example of an extension appdata.
 Unmanaged Flatpak extensions
 ----------------------------
 
-Flatpak also supports `unmanaged extensions`, allowing loading extensions 
-installed externally into ``/var/lib/flatpak/extension`` and 
+Flatpak also supports `unmanaged extensions`, allowing loading extensions
+installed externally into ``/var/lib/flatpak/extension`` and
 ``$XDG_DATA_HOME/flatpak/extension``. This can be useful to expose 
 administrator policies, extensions etc. to Flatpak applications.
+The extension point of unmanaged extensions look no different than
+their regular counterparts.
 
 An example of an unmanaged extension can be found in browsers such as
 `Chromium <https://github.com/flathub/org.chromium.Chromium/blob/dc7f731e7b62199a00bfa3ea3d123ff6d16936dc/org.chromium.Chromium.yaml>`_ 
@@ -397,12 +399,22 @@ The Firefox snippet translates to:
   cleanup-commands:
     - mkdir -p ${FLATPAK_DEST}/etc/firefox
 
-Now the required policy files for Firefox ``pref`` and 
-``policies.json`` can be placed in ``/var/lib/flatpak/extension/org.mozilla.firefox.systemconfig/x86_64/stable/defaults/pref``
+Now the required policy files for Firefox ``pref`` and ``policies.json`` 
+can be placed in ``/var/lib/flatpak/extension/org.mozilla.firefox.systemconfig/x86_64/stable/defaults/pref``
 and ``/var/lib/flatpak/extension/org.mozilla.firefox.systemconfig/x86_64/stable/policies/policies.json``
-respectively.
+respectively on host. These would appear under 
+``/app/etc/firefox/policies/policies.json`` and
+``/app/etc/firefox/defaults/pref`` inside the sandbox.
 
-For Chromium, please look at the `readme <https://github.com/flathub/org.chromium.Chromium>`_.
+Flatpak will only make the drop-ins under those locations available 
+inside the sandbox, the application also needs to support reading them.
+
+For example Firefox `supports <https://hg.mozilla.org/mozilla-central/file/23ee4ac2d048de0aac3fa27ce7eb0925c1903096/xpcom/io/SpecialSystemDirectory.cpp#l198>`_ 
+reading policies from ``/app/etc`` when run under Flatpak and Chromium 
+on Flathub carries patches.
+
+For details on Chromium, please look at the
+`readme <https://github.com/flathub/org.chromium.Chromium>`_.
 
 .. note::