Add a note abort CloudFlare

README.md

@@ -248,6 +248,12 @@ geesefs works with:
 It should also work with any other S3 that implements multipart uploads and
 multipart server-side copy (UploadPartCopy).
 
+Services known to be **broken**:
+* CloudFlare R2. They have at least 2 bugs and don't respond to bug reports:
+  - They throttle requests incorrectly, by returning 403 Forbidden if you exceed
+    5 requests per seconds.
+  - Their listings are broken, see https://github.com/yandex-cloud/geesefs/issues/56.
+
 Important note: you should mount geesefs with `--list-type 2` or `--list-type 1` options
 if you use it with non-Yandex S3.