Fixes for examples (#1408)

* Add various fixes for the examples
* Add the workaround for proposals for `impl_version` 94
* TODO: fix `toPromise` issue for queries with RxJS

docs/examples/promise/04_unsubscribe/index.js

@@ -9,7 +9,7 @@ async function main () {
   const api = await ApiPromise.create();
 
   // Subscribe to chain updates and log the current block number on update.
-  const unsubscribe = await api.rpc.chain.subscribeNewHead((header) => {
+  const unsubscribe = await api.rpc.chain.subscribeNewHeads((header) => {
     console.log(`Chain is at block: #${header.number}`);
   });
 

docs/examples/promise/07_make_transfer_with_allowed_block_permissions_only/package.json

@@ -10,8 +10,7 @@
     "start": "node index.js"
   },
   "dependencies": {
-    "@polkadot/api": "0.80.1",
-    "@polkadot/keyring": "^0.93.1"
+    "@polkadot/api": "*"
   },
   "devDependencies": {
     "rimraf": "^2.6.2"

docs/examples/promise/10_upgrade_chain/index.js

@@ -25,9 +25,11 @@ async function main () {
   const keyring = testKeyring.default();
   const adminPair = keyring.getPair(adminId.toString());
 
-  // Retrieve the runtime to upgrade to
+  // Retrieve the runtime to upgrade
   const code = fs.readFileSync('./test.wasm').toString('hex');
-  const proposal = api.tx.consensus.setCode(`0x${code}`);
+  const proposal = api.tx.system && api.tx.system.setCode
+    ? api.tx.system.setCode(`0x${code}`) // For newer versions of Substrate
+    : api.tx.consensus.setCode(`0x${code}`); // For previous versions
 
   console.log(`Upgrading from ${adminId}, ${code.length / 2} bytes`);