feat(examples/move/nft_marketplace): highlighted the rental extension…

… separately from the marketplace extension and added some mock items for marketplace operations

docs/examples/move/nft_marketplace/sources/item_for_market.move

@@ -0,0 +1,58 @@
+module nft_marketplace::market_items {
+    use iota::package;
+    /// One Time Witness.
+    public struct MARKET_ITEMS has drop {}
+
+
+    fun init(otw: MARKET_ITEMS, ctx: &mut TxContext) {
+        package::claim_and_keep(otw, ctx)
+    }
+
+    public struct TShirt has key, store {
+        id: UID,
+    }
+
+    public struct Jacket has key, store {
+        id: UID,
+    }
+
+    public struct Shoes has key, store {
+        id: UID,
+    }
+
+    public struct Jeans has key, store {
+        id: UID,
+    }
+
+    public fun new_tshirt(ctx: &mut TxContext) {
+        let tshirt = TShirt {
+            id: object::new(ctx),
+        };
+
+        transfer::public_transfer(tshirt, ctx.sender());
+    }
+
+    public fun new_jeans(ctx: &mut TxContext) {
+        let jeans = Jeans {
+            id: object::new(ctx),
+        };
+
+        transfer::public_transfer(jeans, ctx.sender());
+    }
+
+    public fun new_shoes(ctx: &mut TxContext) {
+        let shoes = Shoes {
+            id: object::new(ctx),
+        };
+
+        transfer::public_transfer(shoes, ctx.sender());
+    }
+
+    public fun new_jacket(ctx: &mut TxContext) {
+        let jacket = Jacket {
+            id: object::new(ctx),
+        };
+
+        transfer::public_transfer(jacket, ctx.sender());
+    }
+}