fix "push to bottom" for user tasks in API (#12659)

Also:
- Fix the test for this which has been equally broken.
- Simplify apidoc position info and make consistent in similar routes.
- Replace non-ascii characters in apidoc comment.

website/server/controllers/api-v3/user.js

@@ -1691,9 +1691,9 @@ api.togglePinnedItem = {
  * @apiGroup User
  *
  * @apiParam (Path) {String} path The unique item path used for pinning
- * @apiParam (Path) {Number} position Where to move the task. 0 = top of the list.
- *                                    -1 = bottom of the list.
- *                                    (-1 means push to bottom). First position is 0.
+ * @apiParam (Path) {Number} position Where to move the task.
+ *                                    0 = top of the list ("push to top").
+ *                                   -1 = bottom of the list ("push to bottom").
  *
  * @apiSuccess {Array} data The new pinned items order.
  *