clearer description

Author: notgiorgi

docs/self-host/customize-deployment/environment-variables.mdx

@@ -32,7 +32,7 @@ This is a reference to all environment variables that can be used to configure a
 | `HEADLESS_BROWSER_HOST`                      | Hostname for the headless browser                                                                                                                                                                             |           | —                                                               |
 | `HEADLESS_BROWSER_PORT`                      | Port for the headless browser                                                                                                                                                                                 |           | `3001`                                                          |
 | `ALLOW_MULTIPLE_ORGS`                        | If set to `true`, new users registering on Lightdash will have their own organization, separated from others                                                                                                  |           | `false`                                                         |
-| `LIGHTDASH_IFRAME_EMBEDDING_DOMAINS`         | Allows accessing Lightdash from an iframe                                                                                                                                                                     |           | `false`                                                         |
+| `LIGHTDASH_IFRAME_EMBEDDING_DOMAINS`         | Allows accessing Lightdash from an iframe. Accepts comma separated list of domains                                                                                                                            |           |                                                                 |
 
 Lightdash also accepts all [standard postgres environment variables](https://www.postgresql.org/docs/9.3/libpq-envars.html)