Remove network.target from systemd After dependency (#47)

* Remove `network.target` from systemd `After` dependency

* Remove `network.target` from systemd `After` dependency example in RPM guide

Author: w00000dy

admin/installation.rst

@@ -477,7 +477,7 @@ Provided driver packages:
    .. code-block:: sh
 
      [Unit]
-     After=network.target postgresql.service
+     After=postgresql.service
 
    After editing run ``systemctl daemon-reload`` to reload systemd
    configuration.
@@ -643,7 +643,7 @@ Provided driver packages:
    .. code-block:: sh
 
      [Unit]
-     After=network.target postgresql.service
+     After=postgresql.service
 
    After editing, run ``systemctl daemon-reload`` to reload systemd
    configuration.