[PRAC/cont] Add tooltip for "X" modal/close btn

Adding tooltip for add-modal close "X" btn.

Worth noting:
  - that's better.

core: B-3 / JS-BL

Author: matowdev

core-courses/3-js-basic-level/practicum-js-basic-level/sb-crm-client/js/customTippy.js

@@ -56,6 +56,9 @@
       initTippy('#table-th-change', 'сортировать ⇵', 'bottom', {
         offset: [0, 2],
       });
+      initTippy('.modal__add-header-x-btn', 'закрыть', 'left', {
+        offset: [0, 13],
+      });
     }
 
     initTippyForSearchLogo();