add lint-docs script

package.json

@@ -4,6 +4,7 @@
   "devDependencies": {
     "asar": "^0.11.0",
     "electabul": "~0.0.4",
+    "electron-docs-linter": "^1.0.1",
     "request": "*",
     "standard": "^7.1.2",
     "standard-markdown": "^1.2.1"

script/lint-docs.js

@@ -0,0 +1,19 @@
+#!/usr/bin/env node
+
+const fs = require('fs')
+const path = require('path')
+const lint = require('electron-docs-linter')
+const args = process.argv.slice(2)
+const docsPath = path.join(__dirname, '../docs/api')
+const targetVersion = args[0]
+const outFile = path.join(__dirname, '../electron.json')
+
+if (!targetVersion) {
+  console.error(`Usage: ./script/lint-docs.js <targetVersion>`)
+  process.exit(1)
+}
+
+lint(docsPath, targetVersion).then(function(apis) {
+  fs.writeFileSync(outFile, JSON.stringify(apis, null, 2))
+  console.log(`Wrote ${outFile}`)
+})