chore(lint): add markdownlint, use lint instead of lint:ts witin ci

Author: bufferoverflow

.travis.yml

@@ -7,6 +7,6 @@ script:
   - yarn install
   - commitlint-travis
   - yarn license
-  - yarn lint:ts
+  - yarn lint
   - yarn code:build
   - yarn test:all

package.json

@@ -10,7 +10,7 @@
     "license": "license-checker --onlyAllow 'Apache-2.0; Apache License, Version 2.0; BSD; BSD-2-Clause; BSD-3-Clause; ISC; MIT; Unlicense; WTFPL; CC-BY-3.0; CC0-1.0' --production",
     "type-check:watch": "npm run type-check -- --watch",
     "lint:ts": "eslint . --ext .js,.ts",
-    "lint": "yarn type-check && npm run lint:ts",
+    "lint": "yarn type-check && yarn lint:ts && markdownlint README.md",
     "prepublish": "in-publish && yarn lint && yarn code:build || not-in-publish",
     "release:major": "changelog -M && git commit -a -m 'docs: updated CHANGELOG.md' && yarn version --major && git push origin && git push origin --tags",
     "release:minor": "changelog -m && git commit -a -m 'docs: updated CHANGELOG.md' && yarn version --minor && git push origin && git push origin --tags",