chore: generate API definitions in the project root (#14578)

'out' folder doesn't exist in a freshly cloned repo,
and there are not reasons to use it anyway.

.gitignore

@@ -51,4 +51,8 @@ compile_commands.json
 /npm/dist
 /npm/path.txt
 
-.npmrc
+.npmrc
+
+# Generated API definitions
+electron-api.json
+electron.d.ts

package.json

@@ -60,8 +60,8 @@
     "lint:docs": "remark docs -qf && npm run lint:js-in-markdown && npm run create-typescript-definitions && npm run lint:docs-relative-links",
     "lint:docs-relative-links": "python ./script/check-relative-doc-links.py",
     "lint:js-in-markdown": "standard-markdown docs",
-    "create-api-json": "electron-docs-linter docs --outfile=out/electron-api.json --version=4.0.0-nightly.20180823",
-    "create-typescript-definitions": "npm run create-api-json && electron-typescript-definitions --in=out/electron-api.json --out=out/electron.d.ts",
+    "create-api-json": "electron-docs-linter docs --outfile=electron-api.json --version=4.0.0-nightly.20180823",
+    "create-typescript-definitions": "npm run create-api-json && electron-typescript-definitions --in=electron-api.json --out=electron.d.ts",
     "mock-release": "node ./script/ci-release-build.js",
     "preinstall": "node -e 'process.exit(0)'",
     "publish-to-npm": "node ./script/publish-to-npm.js",