Add documentation and examples (#145)

* Add documentation

* Justification u8a decoding and json encoding (#146)

* Decode Justifications

* Json encoding for justifications

* Bump deps

* Allow extrinsic length encoding to operate on u8a[] (#148)

* Fix config and move generated doc to a subfolder

* Cleanup extrinsic encoding (#150)

* Cleanup extrinsic encoding

* Removed now-defunct type

* Add uncheckedLength encoding

* Add examples

* Ignore package-lock since we use yarn

* Cleanup examples

* Add gitbook config and some base files for the doc

* Do not make full doc mandatory for now

* Add contributing guide, polish doc and samples

* Update the deps of all samples and add yarn scripts
Fix and regenerate the doc

* Fix Contributing guide

docs/examples/07_transfer_dots/README.adoc

@@ -0,0 +1,8 @@
+= Tranfer DOTs
+
+This sample is more 'straight to the point' and shows the easiest way to transfer DOTs from an account to another.
+
+[source, javascript]
+----
+include::index.js[]
+----

docs/examples/07_transfer_dots/index.js

@@ -0,0 +1,42 @@
+const Api = require('@polkadot/api').default
+const WsProvider = require('@polkadot/api-provider/ws').default
+const extrinsics = require('@polkadot/extrinsics').default
+const encodeExtrinsic = require('@polkadot/extrinsics/codec/encode/uncheckedLength').default
+const encodeLength = require('@polkadot/extrinsics/codec/encode/length').default
+const Keyring = require('@polkadot/util-keyring').default
+const storage = require('@polkadot/storage').default
+const BN = require('bn.js')
+
+const Encoder = new TextEncoder()
+const keyring = new Keyring()
+const provider = new WsProvider('ws://127.0.0.1:9944')
+const api = new Api(provider)
+
+async function getAccountIndex (address) {
+  return api.state.getStorage([storage.system.public.accountIndexOf, address])
+}
+
+async function transfer (keyRingFrom, addressTo, amount) {
+  const nextAccountIndex = await getAccountIndex(keyRingFrom.address())
+
+  // encode the call for signing
+  const encoded = encodeExtrinsic(
+    keyRingFrom,
+    nextAccountIndex,
+    extrinsics.staking.public.transfer,
+    [addressTo, amount]
+  )
+
+  await api.author.submitExtrinsic(encoded)
+    .catch(e => console.log)
+}
+
+const Alice = keyring.addFromSeed(Encoder.encode('Alice                           '))
+const addressBob = '5Gw3s7q4QLkSWwknsiPtjujPv3XM4Trxi5d4PgKMMk3gfGTE'
+const amount = new BN(999) // on dev chain, the fee is 1, that makes it a round 1000
+
+console.log(`Crafting and sending an extrinsic for Alice to send Bob ${amount} DOTs`)
+transfer(Alice, addressBob, amount)
+  .then(() => console.log('Done'))
+  .catch((e) => console.log(e))
+  .finally(_ => process.exit(0))

docs/examples/07_transfer_dots/package.json

@@ -0,0 +1,19 @@
+{
+  "name": "07_transfer_dots",
+  "version": "0.1.0",
+  "description": "Example showing how to transfer DOTs",
+  "main": "index.js",
+  "author": "chevdor",
+  "license": "MIT",
+  "scripts": {
+    "clean": "rimraf node_modules",
+    "start": "node index.js"
+  },
+  "dependencies": {
+    "@polkadot/api": "0.29.1",
+    "bn.js": "^4.11.8"
+  },
+  "devDependencies": {
+    "rimraf": "2.6.2"
+  }
+}