Add CONTRIBUTING.md

Author: kmyk

CONTRIBUTING.md

@@ -0,0 +1,16 @@
+# CONTRIBUTING.md
+
+## How to build
+
+``` console
+$ npm install
+$ ./node_modules/.bin/tsc index.ts
+```
+
+## Formatters
+
+``` console
+$ isort crawl.py
+$ yapf --in-place crawl.py
+$ ./node_modules/.bin/prettier -w index.ts
+```