Added optional page number to category commands and shop links (#14)

* Added optional page number to category commands

* Added new shop link format

Author: MackenzieMolloy

docs/shopgui/commands-permissions.md

@@ -13,9 +13,9 @@
 | /sell all                                                                 | Sell all items from your inventory                                             | shopguiplus.sell.all                                      |
 | /shop reload                                                              | Reload the configuration                                                       | shopguiplus.reload                                        |
 | /shop check                                                               | Get information on the item held in hand                                       | shopguiplus.check                                         |
-| /shop [shop name]                                                         | Directly open the specified shop                                               | shopguiplus.shops.SHOP_ID (see **Permissions** paragraph) |
+| /shop [shop name] [page]                                                  | Directly open the specified shop                                               | shopguiplus.shops.SHOP_ID (see **Permissions** paragraph) |
 | /shop [player]                                                            | Directly open the main menu for the player                                     | shopguiplus.others                                        |
-| /shop [player] [shop name]                                                | Open the specified shop to the specified player                                | shopguiplus.others                                        |
+| /shop [player] [shop name] [page]                                         | Open the specified shop to the specified player                                | shopguiplus.others                                        |
 | /shop addmodifier item \<player\> \<shop\> \<item\> \<value\> [buy\|sell] | Add item-specific price modifier                                               | shopguiplus.shop.addmodifier                              |
 | /shop addmodifier shop \<player\> \<shop\> \<value\> [buy\|sell]          | Add shop-specific price modifier                                               | shopguiplus.shop.addmodifier                              |
 | /shop addmodifier global \<player\> \<value\> [buy\|sell]                 | Add global price modifier                                                      | shopguiplus.shop.addmodifier                              |

docs/shopgui/shops-items-setup.md

@@ -717,7 +717,9 @@ Example:
 ```yaml
     1:
       type: shop_link
-      shop: "blocks"
+      link:
+        shop: "blocks"
+        page: 2 # <--- Optional, defaults to page 1 if not set.
       item:
         material: STONE
         quantity: 1