Fix README

plugins/lighthouse/README.md

 # Lighthouse plugin
 
-This plugin issue lighthouse tickets.
+This plugin adds commands to manage [Lighthouse](https://lighthouseapp.com/).
 
 To use it, add `lighthouse` to the plugins array in your zshrc file:
 
@@ -8,8 +8,19 @@ To use it, add `lighthouse` to the plugins array in your zshrc file:
 plugins=(... lighthouse)
 ```
 
-## Aliases
+## Commands
 
-| Alias | Command                                | Description                                          |
-|-------|----------------------------------------|------------------------------------------------------|
-| lho   | `open_lighthouse_ticket`               | Opening lighthouse ticket                            |
\ No newline at end of file
+* `open_lighthouse_ticket <issue>` (alias: `lho`):
+
+  Opens the URL to the issue passed as an argument. To use it, add a `.lighthouse-url`
+  file in your directory with the URL to the individual project.
+
+  Example:
+  ```zsh
+  $ cat .lighthouse-url
+  https://rails.lighthouseapp.com/projects/8994
+
+  $ lho 23
+  Opening ticket #23
+  # The browser goes to https://rails.lighthouseapp.com/projects/8994/tickets/23
+  ```