lisp/org-macs.el: Fix spelling of `org-truly-invisible-p'

* lisp/org-macs.el (org-truly-invisible-p): Fix spelling of name.
* lisp/org-compat.el (org-truely-invisible-p): Add compatibility
  alias for the old name.

lisp/org-compat.el

@@ -752,6 +752,10 @@ context.  See the individual commands for more information."
 
 (define-obsolete-function-alias 'org-get-last-sibling 'org-get-previous-sibling "9.4")
 
+(define-obsolete-function-alias 'org-truely-invisible-p
+  'org-truly-invisible-p "9.6"
+  "Compatibility alias for legacy misspelling of `org-truly-invisible-p'.")
+
 ;;;; Obsolete link types
 
 (eval-after-load 'ol

lisp/org-macs.el

@@ -1151,7 +1151,7 @@ fontification."
 	  (folding-only (memq value '(org-hide-block outline)))
 	  (t value))))
 
-(defun org-truely-invisible-p ()
+(defun org-truly-invisible-p ()
   "Check if point is at a character currently not visible.
 This version does not only check the character property, but also
 `visible-mode'."