Update select2_search.md

Author: cprodhomme

docs/select2_search.md

@@ -25,7 +25,7 @@ If you want to use url helpers, use a `proc` like on the example
 
 ### Options
 
-* `category_id`: Notice we're using the relation field name, not the realtion itself, so you can't use `f.input :category`.
+* `category_id`: Notice we're using the relation field name, not the relation itself, so you can't use `f.input :category`.
 * `url`: This is the URL where to get the results. This URL expects an activeadmin collection Url (like the index action) or anything that uses [ransack](https://github.com/activerecord-hackery/ransack) search gem.
 * `response_root`: **(optional)** If a request to `url` responds with root, you can indicate the name of that root with this attribute. By default, the gem will try to infer the root from url. For example: if `url` is `GET /admin/categories`, the root will be `categories`. If you have a rootless api, you don't need to worry about this attribute.
 * `fields`: an array of field names where to search for matches in the related model (`Category` in this example). If we give many fields, they will be searched with an OR condition.