Fixes xo typo in catch-error-name documentation. (#52)

Should be `unicorn` instead of `xo`.

Author: manovotny

docs/rules/catch-error-name.md

@@ -52,5 +52,5 @@ try {
 You can set the `name` option like this:
 
 ```js
-"xo/catch-error-name": ["error", {"name": "err"}]
+"unicorn/catch-error-name": ["error", {"name": "err"}]
 ```