Accidently added updated docs for hook_civicrm_searchColumns
I committed this by accident - if we merge https://github.com/civicrm/civicrm-core/pull/14184 then it makes sense, otherwise may need to revert https://github.com/civicrm/civicrm-dev-docs/commit/f9298f7e0be57a139f7b49adfb0d0f23e5c33149