fixup: TransferPolicy for Deed

+ Reference `Display` for `Deed` in README.

examples/turnip-town/README.md

@@ -43,8 +43,8 @@ To keep the initial version of the demonstration focussed, the
 following possible extensions have not been implemented, but are left
 as an exercise for the reader!
 
- - Defining **Display for Turnips** to illustrate the size and
-   freshness of Turnips when viewed from the Explorer.
+ - Defining **Display** for `Turnip` and `Deed` to visualize them in
+   Explorers.
  - Using **on-chain randomness** to control how much rain and sun a
    field gets, rather than deciding that off-chain in the game
    service.

examples/turnip-town/move/sources/field.move

@@ -21,12 +21,17 @@ module turnip_town::field {
     use std::vector;
     use sui::math;
     use sui::object::{Self, UID};
+    use sui::package;
+    use sui::transfer;
+    use sui::transfer_policy;
     use sui::tx_context::{Self, TxContext};
 
     use turnip_town::turnip::{Self, Turnip};
 
     friend turnip_town::game;
 
+    struct FIELD has drop {}
+
     struct Field has store {
         slots: vector<Option<Turnip>>,
         water: u64,
@@ -56,6 +61,17 @@ module turnip_town::field {
     const WIDTH: u64 = 4;
     const HEIGHT: u64 = 4;
 
+    fun init(otw: FIELD, ctx: &mut TxContext) {
+        let publisher = package::claim(otw, ctx);
+
+        // Make `Deed`'s transferable between Kiosks, but without any
+        // additional rules.
+        let (policy, cap) = transfer_policy::new<Deed>(&publisher, ctx);
+        transfer::public_share_object(policy);
+        transfer::public_transfer(cap, tx_context::sender(ctx));
+        package::burn_publisher(publisher);
+    }
+
     public fun deed_field(deed: &Deed): address {
         deed.field
     }