Adds Bloom overview README. (#1850)

* Adds Bloom overview README.

* Update README.md

* Incorporates feedback.

* Update README.md

Co-authored-by: Leibale Eidelman <[email protected]>

Author: Simon Prickett

packages/bloom/README.md

@@ -1,3 +1,14 @@
 # @node-redis/bloom
 
-The source code and documentation for this package are in the main [node-redis](https://github.com/redis/node-redis) repo.
+This package provides support for the [RedisBloom](https://redisbloom.io) module, which adds additional probabilistic data structures to Redis.  It extends the [Node Redis client](https://github.com/redis/node-redis) to include functions for each of the RediBloom commands.
+
+To use these extra commands, your Redis server must have the RedisBloom module installed.
+
+RedisBloom provides the following probabilistic data structures:
+
+* Bloom Filter: for checking set membership with a high degree of certainty.
+* Cuckoo Filter: for checking set membership with a high degree of certainty.
+* Count-Min Sketch: Determine the frequency of events in a stream.
+* Top-K: Maintain a list of k most frequently seen items.
+
+For complete examples, see `bloom-filter.js`, `cuckoo-filter.js`, `count-min-sketch.js` and `topk.js` in the Node Redis examples folder.