fix typo: correct method name in CiviCRM documentation of permissions.md

Merge Request Description:

This merge request addresses a typo found in the CiviCRM documentation. The method name CRM_Core_Page_Basic:::checkPermission() was incorrect and has been corrected to CRM_Core_Page_Basic::checkPermission(). This change ensures accuracy and clarity in the documentation, making it easier for users to understand and utilize the provided resources.

Changes Made:

• Corrected method name in CiviCRM documentation from CRM_Core_Page_Basic:::checkPermission() to CRM_Core_Page_Basic::checkPermission().

---