Expand extrinsic decoding example (#2608)

docs/cookbook/blocks.md

@@ -53,8 +53,19 @@ const signedBlock = await this.api.rpc.chain.getBlock();
 
 // the information for each of the contained extrinsics
 signedBlock.block.extrinsics.forEach((ex, index) => {
-  // the extrinsics are decoded by the API
+  // the extrinsics are decoded by the API, human-like view
   console.log(index, ex.toHuman());
+
+  const { isSigned, meta, method: { args, method, section } } = ex;
+
+  // explicit display of name, args & documentation
+  console.log(`${section}.${method}(${args.map((a) => a.toString()).join(', ')})`);
+  console.log(meta.documentation.map((d) => d.toString()).join('\n'));
+
+  // signer/nonce info
+  if (isSigned) {
+    console.log(`signer=${ex.signer.toString()}, nonce=${ex.nonce.toString()}`);
+  }
 });
 ```