[Docs] no-static-element-interactions: tabIndex is written tabindex

see https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/tabindex

linting will also fail if it's `tabIndex` with a capital i

Author: andreasnuesslein

docs/rules/no-static-element-interactions.md

@@ -21,7 +21,7 @@ Indicate the element's role with the `role` attribute:
   onClick={onClickHandler}
   onKeyPress={onKeyPressHandler}
   role="button"
-  tabIndex="0">
+  tabindex="0">
   Save
 </div>
 ```