Fix Level badge

Author: vweevers

README.md

@@ -264,7 +264,7 @@ To sustain [`Level`](https://github.com/Level) and its activities, become a back
 
 [MIT](LICENSE.md) © 2012-present [Max Ogden](https://github.com/maxogden) and [Contributors](CONTRIBUTORS.md).
 
-[level-badge]: http://leveldb.org/img/badge.svg
+[level-badge]: https://leveljs.org/img/badge.svg
 
 [indexeddb]: https://developer.mozilla.org/en-US/docs/Web/API/IndexedDB_API