docs: fix datastore link (#999)

Author: Robert Kiel

doc/CONFIGURATION.md

@@ -210,7 +210,7 @@ const modules = {
 Moreover, the majority of the modules can be customized via option parameters. This way, it is also possible to provide this options through a `config` object. This config object should have the property name of each building block to configure, the same way as the modules specification.
 
 Besides the `modules` and `config`, libp2p allows other internal options and configurations:
-- `datastore`: an instance of [ipfs/interface-datastore](https://github.com/ipfs/interface-datastore/) modules.
+- `datastore`: an instance of [ipfs/interface-datastore](https://github.com/ipfs/js-ipfs-interfaces/tree/master/packages/interface-datastore) modules.
   - This is used in modules such as the DHT. If it is not provided, `js-libp2p` will use an in memory datastore.
 - `peerId`: the identity of the node, an instance of [libp2p/js-peer-id](https://github.com/libp2p/js-peer-id).
   - This is particularly useful if you want to reuse the same `peer-id`, as well as for modules like `libp2p-delegated-content-routing`, which need a `peer-id` in their instantiation.