[documentation] Add section for systemd service and nginx to installation guide (#353)

* add nginx and systemd section

* fix typso

* fix mkdoc and dots in config guide

* specify port

* Update nginx.md

* add section about configuring gts to nginx docs

* Update nginx.md

Co-authored-by: zoe <z8V54gHftevp7LeRVyys$8@DosKq^FeQKUWU!WGpTyiLaxGojNdgnWkaWiv673Twg$aPm&hU>

docs/installation_guide/nginx.md

@@ -0,0 +1,113 @@
+# Reverse proxy with nginx
+
+## Requirements
+
+For this you will need certbot, the certbot nginx plugin and of course nginx.
+These are popular packages so your distro will probably have them.
+
+### Ubuntu
+
+```bash
+sudo apt install certbot python3-certbot-nginx nginx
+```
+
+### Arch
+
+```bash
+sudo pacman -S certbot certbot-nginx nginx
+```
+
+### OpenSuse
+
+```bash
+sudo zypper install nginx python3-certbot python3-certbot-nginx
+```
+
+## Configure GoToSocial
+
+In your GoToSocial config turn off letsencrypt.
+First open the file in your text editor.
+
+```bash
+sudoedit /gotosocial/config.yaml
+```
+
+Then set `letsencrypt-enabled: false`.
+
+If GoToSocial is already running, restart it.
+
+```bash
+sudo systemctl restart gotosocial.service
+```
+
+Or if you don't have a systemd service just restart it manually.
+
+## Set up nginx
+
+First we will set up nginx to serve GoToSocial as unsecured http and then later use certbot to automatically upgrade to https.
+Please do not try to use it until that's done or you'll be transmitting passwords over clear text.
+
+First we'll write a configuration for nginx and put it in `/etc/nginx/sites-available`.
+
+```bash
+sudo mkdir /etc/nginx/sites-available/
+sudoedit /etc/nginx/sites-available/yourgotosocial.url.conf
+```
+
+The file you're about to create should look a bit like this:
+
+```nginx.conf
+server {
+  listen 80;
+  server_name example.com;
+  location / {
+    proxy_pass http://localhost:8080;
+    proxy_set_header Host $host;
+  }
+}
+```
+
+Change `proxy_pass` to the ip and port that you're actually serving GoToSocial on and change `server_name` to your own domain name.
+If your domain name is `gotosocial.example.com` then `server_name gotosocial.example.com;` would be the correct value.
+If you're running GoToSocial on another machine with the local ip of 192.168.178.69 and on port 8080 then `proxy_pass http://192.168.178.69:8080;` would be the correct value.
+
+Next we'll need to link the file we just created to the folder that nginx reads configurations for active sites from.
+
+```bash
+sudo mkdir /etc/nginx/sites-enabled
+sudo ln -s /etc/nginx/sites-available/yourgotosocial.url.conf /etc/nginx/sites-enabled/
+```
+
+Now check for configuration errors.
+
+```bash
+sudo nginx -t
+```
+
+If everything is fine you should get this as output:
+
+```
+nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
+nginx: configuration file /etc/nginx/nginx.conf test is successful
+```
+
+Everything working? Great! Then restart nginx to load your new config file.
+
+```bash
+sudo systemctl restart nginx
+```
+
+## Setting up SSL with certbot
+
+You should now be able to run certbot and it will guide you through the steps required to enable https for your instance.
+
+```bash
+sudo certbot --nginx
+```
+
+After you do, it should have automatically edited your configuration file to enable https.
+Just reload it one last time and after that you should be good to go!
+
+```bash
+sudo systemctl restart nginx
+```