Update SNAP Installation instructions

docs/content/doc/installation/from-package.en-us.md

@@ -47,9 +47,68 @@ pacman -S gitea
 
 There is a [Gitea Snap](https://snapcraft.io/gitea) package which follows the latest stable version.
 
+### This guide was tested with Ubuntu 20.04 and MariaDB:
+
+* Install needed packages:
+
+```sh
+sudo snap install gitea
+sudo apt install nginx mariadb-server
+```
+* Improve the security of your MariaDB Installation
+
 ``sh
-snap install gitea
-``
+sudo mysql_secure_installation``
+More information can be found on this website: https://mariadb.com/kb/en/mysql_secure_installation/
+
+* Create your database and database user:
+
+```sql
+sudo mysql -u root -p
+        CREATE DATABASE gitea;
+        GRANT ALL PRIVILEGES ON gitea.* TO 'gitea'@'localhost' IDENTIFIED BY 'the same password for gitea config';
+        FLUSH PRIVILEGES;
+        QUIT;
+```
+Detailed information about Database preperation can be found by following this link: https://docs.gitea.io/en-us/database-prep/
+
+* Create nginx config to pass traffic to port 3000:
+
+```sh
+sudo nano /etc/nginx/conf.d/gitea.conf
+```
+
+* The Nginx config should look something like the following code block.
+To use `HTTPS`, you should additionally pass a certificate and redirect all traffic to port 443.
+The following link covers some information about a secure setup:
+https://docs.gitea.io/en-us/https-setup/
+
+This link may help to create a secure nginx configuration: https://ssl-config.mozilla.org/#server=nginx&version=2.4.41&config=intermediate&openssl=1.1.1d&guideline=5.6
+
+For junior users this blogpost may help to get you started with securing your installation with nginx as reverse proxy and certbot for certificate issuing:
+https://www.nginx.com/blog/using-free-ssltls-certificates-from-lets-encrypt-with-nginx/
+
+
+```nginx
+server {
+    listen 80;
+    server_name gitea.example.com;
+
+    location / {
+        proxy_pass http://localhost:3000;
+    }
+}
+```
+More information about reverse proxies can be found here:
+https://docs.gitea.io/en-us/reverse-proxies/
+* Restart nginx
+```sh
+sudo systemctl restart nginx
+```
+
+* Create correct DNS entry on your DNS Server if not done already
+* Configure your gitea settings
+	The config file for the Snap can be found here if you want to make changes later: /var/snap/gitea/common/conf/app.ini
 
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