`/v2/achievements`: Add objective hints

[darthmaim]

Feature Description

Some objectives have hints in game, which are currently not exposed in the API.

Implementation

Add an optional hint to the bits.

Example

 {
   "id": 7048,
   "name": "Sorrow's Lost",
   "bits": [
     {
       "type": "Item",
       "id": 100598,
+      "hint": "Dadga needs to speak with you in the Wizard's Tower."
     },
     // ...
   ]
 }

Anything else?

Example: The achievement Sorrow's Lost has hints on the objectives, for example the hint for the first item is:

Dadga needs to speak with you in the Wizard's Tower.