Subscriptions return unsubscribe/dispose function (#527)

* Combinator return unsubscribe/dispose function

* Submittable extrinsics return UnsubFunction

* RPC methods with unsub callback returns

* Update changelog, bump version

* CHANGELOG typo

* Fix combinator unsubscribes

* Be explicit in returns for UnsubFunction (combineLatest)

packages/types/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@polkadot/types",
-  "version": "0.35.19",
+  "version": "0.36.0",
   "description": "Implementation of the Parity codec",
   "main": "index.js",
   "keywords": [
@@ -30,8 +30,8 @@
   "homepage": "https://github.com/polkadot-js/api/tree/master/packages/types#readme",
   "dependencies": {
     "@babel/runtime": "^7.2.0",
-    "@polkadot/keyring": "^0.33.27",
-    "@polkadot/util": "^0.33.27",
+    "@polkadot/keyring": "^0.33.28",
+    "@polkadot/util": "^0.33.28",
     "core-js": "^2.6.1"
   }
 }

packages/types/src/scripts/MetadataMd.ts

@@ -63,13 +63,12 @@ function addRpc () {
       }).join(', ');
       const type = '`' + method.type + '`';
       const isSub = method.isSubscription;
-      const renderMethod = `${md}\n▸ **${methodName}**(${args})`;
+      const renderMethod = `${md}\n▸ **${methodName}**(${args}`;
       const renderReturnType = `: ${type}`;
       const renderSignature = `${renderMethod}${renderReturnType}`;
-      const renderSignatureSub = `${renderMethod}**.subscribe**(CALLBACK)${renderReturnType}`;
       const renderSummary = `${method && method.description ? `\n- **summary**: ${method.description}\n` : `\n\n`}`;
 
-      return isSub ? `${renderSignatureSub}${renderSummary}` : `${renderSignature}${renderSummary}`;
+      return `${renderSignature}${isSub ? ', CALLBACK' : ''})${renderSummary}`;
     }, renderSection);
   }, renderHeading + renderAnchors);
 }