doc(basic_bitcoin): add icp ninja link (#1234)

Changes to the basic_bitcoin example README.md:

* Add a link to ICP ninja
* Remove reference to pre-deployed canister
* Fix invalid candid args in get_block_headers command
* Fix invalid regtest address

Author: mducroux

rust/basic_bitcoin/README.md

@@ -38,7 +38,13 @@ For background on the ICP<>BTC integration, refer to the [Learn Hub](https://lea
 - [x] [Local Bitcoin testnet (regtest)](https://internetcomputer.org/docs/build-on-btc/btc-dev-env#create-a-local-bitcoin-testnet-regtest-with-bitcoind)
 - [x] On macOS, an `llvm` version that supports the `wasm32-unknown-unknown` target is required. This is because the Rust `bitcoin` library relies on the `secp256k1-sys` crate, which requires `llvm` to build. The default `llvm` version provided by XCode does not meet this requirement. Instead, install the [Homebrew version](https://formulae.brew.sh/formula/llvm), using `brew install llvm`.
 
-## Building and deploying the smart contract
+## Deploying from ICP Ninja
+
+This example can be deployed directly to the Internet Computer using ICP Ninja, where it will connect to Bitcoin **testnet4**. Note: Canisters deployed using ICP Ninja remain live for 50 minutes after signing in with your Internet Identity (accessible via the top-right button in ICP Ninja).
+
+[![](https://icp.ninja/assets/open.svg)](https://icp.ninja/editor?g=https://github.com/dfinity/examples/tree/master/rust/basic_bitcoin)
+
+## Building and deploying the smart contract locally
 
 ### 1. Clone the examples repo
 
@@ -55,9 +61,9 @@ dfx start --enable-bitcoin --bitcoin-node 127.0.0.1:18444
 ```
 This starts a local canister execution environment with Bitcoin support enabled.
 
-### 3. Start the Bitcoin testnet (regtest)
+### 3. Start Bitcoin regtest
 
-Open another terminal window (terminal 2) and run the following to start the local Bitcoin testnet:
+Open another terminal window (terminal 2) and run the following to start the local Bitcoin regtest network:
 
 ```bash
 bitcoind -conf=$(pwd)/bitcoin.conf -datadir=$(pwd)/bitcoin_data --port=18444
@@ -78,11 +84,6 @@ What this does:
 
 Your smart contract is live and ready to use! You can interact with it using either the command line or the Candid UI (the link you see in the terminal).
 
-> [!NOTE]
-> You can also interact with a pre-deployed version of the `basic_bitcoin` example running on the IC mainnet and configured to interact with Bitcoin **testnet4**.
->
-> Access the Candid UI of the example: https://a4gq6-oaaaa-aaaab-qaa4q-cai.raw.icp0.io/?id=vvha6-7qaaa-aaaap-ahodq-cai
-
 ## Generating Bitcoin addresses
 
 The example demonstrates how to generate and use the following address types:
@@ -139,7 +140,7 @@ Example:
 
 ```bash
 dfx canister call basic_bitcoin send_from_p2pkh_address '(record {
-  destination_address = "tb1ql7w62elx9ucw4pj5lgw4l028hmuw80sndtntxt";
+  destination_address = "bcrt1qg8qknn6f3txqg97gt8ca0ctya0vw7ep6d02qmt";
   amount_in_satoshi = 4321;
 })'
 ```
@@ -158,9 +159,9 @@ The function returns the transaction ID. When interacting with the contract depl
 You can query historical block headers:
 
 ```bash
-dfx canister call basic_bitcoin get_block_headers '(10: nat32)'
+dfx canister call basic_bitcoin get_block_headers '(10: nat32, null)'
 # or a range:
-dfx canister call basic_bitcoin get_block_headers '(0: nat32, 11: nat32)'
+dfx canister call basic_bitcoin get_block_headers '(10: nat32, opt (11: nat32))'
 ```
 
 This calls `bitcoin_get_block_headers`, which is useful for blockchain validation or light client logic.

rust/basic_bitcoin/dfx.json

@@ -14,7 +14,8 @@
       ],
       "package": "basic_bitcoin",
       "type": "custom",
-      "wasm": "target/wasm32-unknown-unknown/release/basic_bitcoin.wasm"
+      "wasm": "target/wasm32-unknown-unknown/release/basic_bitcoin.wasm",
+      "init_arg": "(variant { testnet })"
     }
   },
   "defaults": {