Merge pull request #333 from WICG/clarify-storagefoundation-relation

Add a warning that files are not shared between Storage Foundation and OPFS.

AccessHandle.md

@@ -60,6 +60,11 @@ System](https://docs.google.com/document/d/121OZpRk7bKSF7qU3kQLqAEUVSNxqREnE98ma
 [Recommendation for Augmented
 OPFS](https://docs.google.com/document/d/1g7ZCqZ5NdiU7oqyCpsc2iZ7rRAY1ZXO-9VoG4LfP7fM).
 
+Although this proposal is the successor "in spirit" to the Storage Foundation
+API, the two APIs operate on entirely different sets of files. There exists no
+way of accessing a file stored through Storage Foundation API using the Origin
+Private File System, and vice versa.
+
 ## Goals & Use Cases
 
 Our goal is to give developers flexibility by providing generic, simple, and
@@ -86,6 +91,9 @@ System](https://wicg.github.io/file-system-access/#sandboxed-filesystem), and
 doesn't currently consider changes to the rest of File System Access API or how
 files in the host machine are accessed.
 
+This proposal does not consider accessing files stored using the Storage 
+Foundation API through OPFS or vice versa.
+
 ## What makes the new surface fast?
 
 There are a few design choices that primarily contribute to the performance of