Remove configuration reloading

Removed the deprecated configuration reloading code. Added a entry into
the release notes that states this and the fact that it was deprecated in
2.2.

include/maxscale/config.h

@@ -529,13 +529,6 @@ unsigned int config_nbpolls(void);
  */
 unsigned int config_pollsleep(void);
 
-/**
- * @brief Reload the configuration
- *
- * @return True if reloading was successful
- */
-bool config_reload(void);
-
 /**
  * @brief List all path parameters as JSON
  *