docs: Add docs for HTTPS and SSL in README

packages/server/README.md

@@ -187,6 +187,35 @@ const server = new ProxyServer({
 server.start();
 ```
 
+#### HTTPS and SSL certificates
+
+The server supports HTTPS enabling the option `enableHTTPS` with **multiple domains**. It is fully compatible with [LetsEncrypt](https://letsencrypt.org/) and [certbot](https://certbot.eff.org/) but also with custom SSL certificates.
+
+Once HTTPS is enabled, the server detects the domain in each request and tries to find a SSL certificate. If the certificate does not exist, it uses an untrusted temporary SSL certificate valid for 1 day.
+
+Valid SSL certificates must be provided, using LetsEncrypt or another provider.
+
+##### Using LetsEncrypt
+
+Install the `certbot` following the instructions [here](https://certbot.eff.org/instructions). Then run the server with the `enableHTTPS` option as `true` and with the `port` set to `443`.
+
+When the server is running, just add the certificate into the server:
+
+```bash
+sudo certbot certonly --webroot --keep-until-expiring --agree-tos -w $ABSOLUTE_PATH/letsencrypt -d DOMAIN
+```
+
+The server automatically adds the necessary routes needed for letsencrypt to validate the server. Once the certificate is generated, restart the server.
+
+##### Using custom SSL certificates
+
+If using LetsEncrypt is not an option, you can provide your custom certificates using the `sslCertificatesDirectory` option. The option must have the path for a directory where the certificates are placed following this structure:
+
+- Certificates directory folder:
+  - [folder named as each domain]
+    - `privkey.pem`
+    - `fullchain.pem`
+
 ### Configuration options
 
 ##### Common options