docs(readme): fix typo

Author: teppeis

README.md

@@ -79,4 +79,4 @@ Note: only `compilerOptions` field in tsconfig.json is applied.
 [deps-image]: https://david-dm.org/power-assert-js/espower-typescript.svg
 [deps-url]: https://david-dm.org/power-assert-js/espower-typescript
 [node-version]: https://img.shields.io/badge/Node.js%20support-v4,v6,v7-brightgreen.svg
-[license]: https://img.shields.io/npm/l/essower-typescript.svg
+[license]: https://img.shields.io/npm/l/espower-typescript.svg