add custom domain docs (#13)

docs/usage.md

@@ -184,7 +184,7 @@ lando yarn              Runs yarn commands
 
 Note that you can define your own commands by using out [tooling framework](https://docs.lando.dev/config/tooling.md). Also check out the guides for the powerful [DB Export](https://docs.lando.dev/guides/db-export.md) and [DB Import](https://docs.lando.dev/guides/db-import.md) commands.
 
-Also, check out the [Lagoon CLI Docs](https://amazeeio.github.io/lagoon-cli/commands/lagoon/) for more information on using `lando lagoon`.
+Also, check out the [Lagoon CLI Docs](https://uselagoon.github.io/lagoon-cli/commands/lagoon/) for more information on using `lando lagoon`.
 
 ### Mailhog
 
@@ -252,4 +252,18 @@ lando push -d main -f main
 lando push --database none --files none
 ```
 
+## Customizing your domain or using a non `lndo.site` domain
+
+As per the general Lando [Proxy](https://docs.lando.dev/config/proxy.html) instructions, it is possible to configure custom domains (i.e. `myapp.lndo.site` or `foo.bar.xyz`) for your site.  However, as the default Lagoon base images are built slightly differently to the default Lando ones, you need to specify the port  to route the request to (usually 8080 for nginx):
+
+Add the following lines to your .lando.yml file
+
+```yaml
+proxy:
+  nginx:
+    - myapp.lndo.site:8080
+    - foo.bar.xyz:8080
+```
+Your app can then be accessed via the `myapp.lndo.site` or `foo.bar.xyz` URL.  Note that this will override any autogenerated URLs.
+
 <RelatedGuides tag="Lagoon"/>