fix(keyboard): deprecate specialCharMap (#738)

Author: ph-fritsche

src/keyboard/specialCharMap.ts

@@ -1,3 +1,8 @@
+/**
+ * @deprecated This list of strings with special meaning is no longer necessary
+ * as we've introduced a standardized way to describe any keystroke for `userEvent`.
+ * @see https://testing-library.com/docs/ecosystem-user-event#keyboardtext-options
+ */
 export const specialCharMap = {
   arrowLeft: '{arrowleft}',
   arrowRight: '{arrowright}',