mention core library and infra agnosticism

Author: g-husam

docs/README.md

@@ -1,6 +1,7 @@
 # ML Flashpoint
 
 ML Flashpoint is a memory-first, lightning-fast, ready-to-use ML checkpointing library.
+It is infrastructure and scheduler agnostic, with native integrations for certain frameworks, and a core library for custom use cases.
 
 Check out the [User Guide](user-guide.md) to get started.
 

docs/user-guide.md

@@ -1,6 +1,10 @@
 # User Guide
 
 Below are instructions for using ML Flashpoint with the different frameworks supported.
+For finer-grain control, use the [core](https://github.com/google/ml-flashpoint/tree/main/src/ml_flashpoint/core) library APIs, which the framework adapters build on top of.
+The adapters also provide a good working example of how to use the core library.
+
+If interested in a native integration with another framework, please let us know by creating a [feature request](https://github.com/google/ml-flashpoint/issues/new?template=feature_request.md) or upvoting an [existing one](https://github.com/google/ml-flashpoint/issues?q=is%3Aissue%20state%3Aopen%20label%3Aenhancement).
 
 ## Install