:docs: fix(gpg) removing the old gpg singature from the manual

Signed-off-by: Benoit Mortier <benoit.mortier@fusiondirectory.org>

source/fusiondirectory/plugins/dsa/images/.directory

-[Dolphin]
-Timestamp=2019,6,4,14,35,18
-Version=3
-ViewMode=2

source/gpg/gpg-keys.rst

@@ -3,11 +3,11 @@
 Getting the official GPG keys to active package signature
 ---------------------------------------------------------
 
-Our packages for Debian and Centos are signed with the official gpg
+Our packages for Debian, Ubuntu and Centos are signed with the official gpg
 key of the project.
 
-Getting the new official gpg key
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Getting the official gpg key
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 * Asking the key from the keyserver
 

source/gpg/index.rst

@@ -7,4 +7,3 @@ All our packages are signed by a gpg key
    :maxdepth: 2
 
    gpg-keys.rst
-   old-gpg-keys.rst

source/gpg/old-gpg-keys.rst

-.. _old-gpg-keys-label:
-
-Getting the old official GPG keys to active package signature
--------------------------------------------------------------
-
-.. warning::
-
-   This key is no longer used it was changed after FusionDirectory 1.2.3
-   and only usefull if you try to reinstall an old version
-
-Getting the old official gpg key
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-.. code-block:: shell
-
-    gpg --keyserver keys.gnupg.net --recv-key 0xD744D55EACDA69FF
-
-    gpg --export -a "FusionDirectory Project Signing Key <contact@fusiondirectory.org>" > FD-archive-key
-
-Adding the key to apt for Debian/Ubuntu
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-.. code-block:: shell
-
-   apt-key add FD-archive-key
-
-Adding the key for RPM into Centos
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-.. code-block:: shell
-
-   cp FD-archive-key /etc/pki/rpm-gpg/RPM-GPG-KEY-FUSIONDIRECTORY
-
-   rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-FUSIONDIRECTORY