chore: update docs/core-api/README (#4159)

Author: BigLep

docs/core-api/README.md

@@ -1,6 +1,11 @@
 # IPFS Core API
 
-This directory contains the description of the core IPFS API. In order to be considered "valid", an IPFS core implementation must expose the API described here. You can also use this loose spec as documentation for consuming the core APIs.
+This directory contains the description of the core JS IPFS API. In order to be considered "valid", a JS IPFS core implementation must expose the API described here. 
+This abstraction allows for different implementations including:
+1. Full JavaScript native implementation
+2. Delgate implementation that invokes another IPFS implementation (e.g., Kubo)
+
+You can use this loose spec as documentation for consuming the core APIs.  
 
 It is broken up into the following sections:
 
@@ -21,3 +26,6 @@ It is broken up into the following sections:
 * [REPO.md](REPO.md)
 * [STATS.md](STATS.md)
 * [SWARM.md](SWARM.md)
+
+## History
+This API was created based off the [Kubo RPC HTTP API](https://docs.ipfs.io/reference/kubo/rpc/).  There is no guarantee they stay fully in sync.