Adding explicit wildcard to $EXTRA_DOMAINS

Via Discord (https://discord.com/channels/354974912613449730/354974913049919488/736268903843627049) learned that `EXTRA_DOMAINS` supports wildcards. An example making this explicit may be helpful for others attempting to mimic setups like I have. 😃

Author: jmuchovej

readme-vars.yml

@@ -56,7 +56,7 @@ opt_param_env_vars:
   - { env_var: "DUCKDNSTOKEN", env_value: "", desc: "Required if `VALIDATION` is set to `duckdns`. Retrieve your token from https://www.duckdns.org" }
   - { env_var: "EMAIL", env_value: "", desc: "Optional e-mail address used for cert expiration notifications." }
   - { env_var: "ONLY_SUBDOMAINS", env_value: "false", desc: "If you wish to get certs only for certain subdomains, but not the main domain (main domain may be hosted on another machine and cannot be validated), set this to `true`" }
-  - { env_var: "EXTRA_DOMAINS", env_value: "", desc: "Additional fully qualified domain names (comma separated, no spaces) ie. `extradomain.com,subdomain.anotherdomain.org`" }
+  - { env_var: "EXTRA_DOMAINS", env_value: "", desc: "Additional fully qualified domain names (comma separated, no spaces) ie. `extradomain.com,subdomain.anotherdomain.org,*.anotherdomain.org`" }
   - { env_var: "STAGING", env_value: "false", desc: "Set to `true` to retrieve certs in staging mode. Rate limits will be much higher, but the resulting cert will not pass the browser's security test. Only to be used for testing purposes." }
 opt_param_usage_include_vols: false
 opt_param_volumes: