Merge pull request #640 from cj89898/docs/wiki

Update Placeholders.md

wiki/Placeholders.md

@@ -568,6 +568,8 @@ A majority of these Expansions are maintained by the PlaceholderAPI team and can
     Requires `mat:` modifier. Strictly checks the name and lore for an item. (If a Stone named `Test` is in your inventory, and you're using `%checkitem_mat:stone,strict%`, it will return false)
   - `inhand`  
     Check if the item is in the player's hand (Also checks off-hand)
+  - `inslot`  
+    Check if the item is in a specific slot ([Click here for valid slots](https://proxy.spigotmc.org/d3e11b631e22f45fc07c3fcd1c7000b2245fed78?url=http%3A%2F%2Fi.imgur.com%2F3YCrfC8.png))
   
   **Notes:**  
   - * means case-sensitive