docs(readme): fix incorectly rendered table

Author: Tinsh

README.md

@@ -7,7 +7,7 @@ Released under an [MIT license](https://kohana.top/license), Kohana can be used
 
 ## Supported versions
 | Version    | PHP Compatibility                  | Initial Release     |
-|------------|----------------------------------------------------------|
+| ---------- | ---------------------------------- | ------------------- |
 | Kohana 3.3 | PHP 5.3, PHP 5.4, PHP 5.5, PHP 5.6 | October 23th, 2012  |
 | Kohana 3.4 | PHP 5.6, PHP 7.0                   | December 25th, 2018 |