elaborate on some comments in example config files

config/config.example.js

@@ -42,7 +42,7 @@ module.exports = {
  *
  *  In a production instance this should be available ONLY over HTTPS
  *  using the default port for HTTPS (443) ie. https://cryptpad.fr
- *  In such a case this should be handled by NGINX, as documented in
+ *  In such a case this should be also handled by NGINX, as documented in
  *  cryptpad/docs/example.nginx.conf (see the $main_domain variable)
  *
  */

docs/example.nginx.conf

@@ -32,6 +32,9 @@ server {
     server_name your-main-domain.com your-sandbox-domain.com;
 
     # You'll need to Set the path to your certificates and keys here
+    # IMPORTANT: this config is intended to serve assets for at least two domains
+    # (your main domain and your sandbox domain). As such, you'll need to generate a single SSL certificate
+    # that includes both domains in order for things to work as expected.
     ssl_certificate         /home/cryptpad/.acme.sh/your-main-domain.com/fullchain.cer;
     ssl_certificate_key     /home/cryptpad/.acme.sh/your-main-domain.com/your-main-domain.com.key;
     ssl_trusted_certificate /home/cryptpad/.acme.sh/your-main-domain.com/ca.cer;