Update mhe link definition

* lisp/org-mhe.el ("mhe"): Define link with org-link-set-parameters.

lisp/org-mhe.el

@@ -74,8 +74,7 @@ supported by MH-E."
 (defvar mh-search-regexp-builder)
 
 ;; Install the link type
-(org-add-link-type "mhe" 'org-mhe-open)
-(add-hook 'org-store-link-functions 'org-mhe-store-link)
+(org-link-set-parameters "mhe" :follow #'org-mhe-open :store #'org-mhe-store-link)
 
 ;; Implementation
 (defun org-mhe-store-link ()