Fix upgrading

Author: ericproulx

UPGRADING.md

@@ -5,9 +5,9 @@ Upgrading Grape
 
 ### `content_type` vs `api.format` inside API
 
-Before 2.3.0, `content_type` would have priority over `env['api.format']` when set in an API. The priority has been flipped and `env['api.format']` will be checked first.
+Before 2.3.0, `content_type` had priority over `env['api.format']` when set in an API, which was incorrect. The priority has been flipped and `env['api.format']` will be checked first.
 In addition, the function `api_format` has been added. Instead of setting `env['api.format']` directly, you can call `api_format`.
-See [#2506] (https://github.com/ruby-grape/grape/pull/2506) for more information.
+See [#2506](https://github.com/ruby-grape/grape/pull/2506) for more information.
 
 #### Remove Deprecated Methods and Options