docs: add stats.bw* to README (#1267)

Author: hacdias

README.md

@@ -347,7 +347,9 @@ A complete API definition is in the works. Meanwhile, you can learn how to you u
 
 - [stats](https://github.com/ipfs/interface-ipfs-core/tree/master/SPEC/STATS.md)
   - [`ipfs.stats.bitswap([callback])`](https://github.com/ipfs/interface-ipfs-core/tree/master/SPEC/STATS.md#bitswap)
-  - [`ipfs.stats.bw([options, callback])`](https://github.com/ipfs/interface-ipfs-core/tree/master/SPEC/STATS.md#bw) (not implemented, yet!)
+  - [`ipfs.stats.bw([options, callback])`](https://github.com/ipfs/interface-ipfs-core/tree/master/SPEC/STATS.md#bw)
+  - [`ipfs.stats.bwPullStream([options]) -> Pull Stream`](https://github.com/ipfs/interface-ipfs-core/tree/master/SPEC/STATS.md#bwpullstream)
+  - [`ipfs.stats.bwReadableStream([options]) -> Readable Stream`](https://github.com/ipfs/interface-ipfs-core/tree/master/SPEC/STATS.md#bwreadablestream)
   - [`ipfs.stats.repo([options, callback])`](https://github.com/ipfs/interface-ipfs-core/tree/master/SPEC/STATS.md#repo)
 
 - [config](https://github.com/ipfs/interface-ipfs-core/tree/master/SPEC/CONFIG.md)