Update readme with new options

README.md

@@ -98,7 +98,9 @@ decide to view it as a coll, and with that viewer selected, `deref` would
 return a list of pairs. Not many viewers implement this functionality
 currently, but expect more to do so in the future.
 
-### Themes
+### Options
+
+#### Themes
 
 There are currently three built-in themes:
 
@@ -113,6 +115,16 @@ Which can be passed as an option to `p/open`:
   {:portal.colors/theme :portal.colors/nord})
 ```
 
+#### Launcher
+
+The following options can be passed to the `p/open` function to change how the
+UI is launched:
+
+| Option                  | Description                | If not specified     |
+|-------------------------|----------------------------|----------------------|
+| `:portal.launcher/port` | Port used to access UI     | random port selected |
+| `:portal.launcher/host` | Hostname used to access UI | "localhost"          |
+
 ## Datafy and Nav
 
 There is one exception to the behavior described above for the UI,