Update docs

scripts/release/synchronize-versions.js

@@ -0,0 +1,16 @@
+#!/usr/bin/env node
+
+// Synchronizes the version in contracts/package.json with the one in package.json.
+// This is run automatically when npm version is run.
+
+const fs = require('fs');
+const cp = require('child_process');
+
+setVersion('contracts/package.json');
+
+function setVersion (file) {
+  const json = JSON.parse(fs.readFileSync(file));
+  json.version = process.env.npm_package_version;
+  fs.writeFileSync(file, JSON.stringify(json, null, 2) + '\n');
+  cp.execFileSync('git', ['add', file]);
+}