[Docs] Linux Service Edit (#9633)

* Rename h3 title

* Add intro

Should work on Ubuntu Xenial, but should work on any Linux distros.

* Indirect edit files

Instead of providing `sudo vim`, invite to edit files.

* enable now instead of enable and start

* Re-add systemctl enable && systemctl start

* Revert service enablement back to status quo

* Add enable now counterpart for systemd > v220

* Apply suggestions from @sapk

Strip `vim` from editor usage

Co-Authored-By: Antoine GIRARD <sapk@users.noreply.github.com>

Co-authored-by: Antoine GIRARD <sapk@users.noreply.github.com>

docs/content/doc/installation/run-as-service-in-ubuntu.en-us.md

@@ -13,16 +13,13 @@ menu:
     identifier: "linux-service"
 ---
 
-### Run as service in Ubuntu 16.04 LTS
+### Run Gitea as Linux service
 
-#### Using systemd
+You can run Gitea as service, using either systemd or supervisor. The steps below tested on Ubuntu 16.04, but those should work on any Linux distributions (with little modification).
 
-Run the below command in a terminal:
-```
-sudo vim /etc/systemd/system/gitea.service
-```
+#### Using systemd
 
-Copy the sample [gitea.service](https://github.com/go-gitea/gitea/blob/master/contrib/systemd/gitea.service).
+Copy the sample [gitea.service](https://github.com/go-gitea/gitea/blob/master/contrib/systemd/gitea.service) to `/etc/systemd/system/gitea.service`, then edit the file with your favorite editor.
 
 Uncomment any service that needs to be enabled on this host, such as MySQL.
 
@@ -35,6 +32,10 @@ sudo systemctl enable gitea
 sudo systemctl start gitea
 ```
 
+If you have systemd version 220 or later, you can enable and immediately start Gitea at once by:
+```
+sudo systemctl enable gitea --now
+```
 
 #### Using supervisor
 
@@ -49,19 +50,20 @@ Create a log dir for the supervisor logs:
 mkdir /home/git/gitea/log/supervisor
 ```
 
-Open supervisor config file in a file editor:
-```
-sudo vim /etc/supervisor/supervisord.conf
-```
-
 Append the configuration from the sample
-[supervisord config](https://github.com/go-gitea/gitea/blob/master/contrib/supervisor/gitea).
+[supervisord config](https://github.com/go-gitea/gitea/blob/master/contrib/supervisor/gitea) to `/etc/supervisor/supervisord.conf`.
 
-Change the user (git) and home (/home/git) settings to match the deployment
-environment. Change the PORT or remove the -p flag if default port is used.
+Using your favorite editor, change the user (git) and home
+(/home/git) settings to match the deployment environment. Change the PORT
+or remove the -p flag if default port is used.
 
 Lastly enable and start supervisor at boot:
 ```
 sudo systemctl enable supervisor
 sudo systemctl start supervisor
 ```
+
+If you have systemd version 220 or later, you can enable and immediately start supervisor by:
+```
+sudo systemctl enable supervisor --now
+```