Update README.md

Author: dorianbrown

README.md

@@ -2,7 +2,9 @@
 
 ![Build Status](https://github.com/dorianbrown/rank_bm25/workflows/pytest/badge.svg)
 [![PyPI version](https://badge.fury.io/py/rank-bm25.svg)](https://badge.fury.io/py/rank-bm25)
+![PyPI - Downloads](https://img.shields.io/pypi/dm/rank_bm25)
 [![DOI](https://zenodo.org/badge/166720547.svg)](https://zenodo.org/badge/latestdoi/166720547)
+![PyPI - License](https://img.shields.io/pypi/l/rank_bm25)
 
 A collection of algorithms for querying a set of documents and returning the ones most relevant to the query. The most common use case for these algorithms is, as you might have guessed, to create search engines.