Add LetsEncrypt host to env and docker-compose files

An update was made in the environment variable `.env` file, where a new host for LetsEncrypt was added. This LetsEncrypt host was then also added to the `docker-compose.yml` file. These changes equip the application with SSL encryption capabilities.

docker-compose.yml

@@ -13,6 +13,7 @@ services:
   nginx:
     image: nginx:latest
     environment:
+      - LETSENCRYPT_HOST=${LETSENCRYPT_HOST}
       - VIRTUAL_HOST=${VIRTUAL_HOST}
       - VIRTUAL_PORT=${VIRTUAL_PORT}
     volumes: