Update README.md

Author: normanrz

README.md

@@ -1,8 +1,4 @@
-# zarr-extensions (PREVIEW)
-
-Currently, this repository is in preview mode. It will become the registry for Zarr v3 extensions as soon as [the changes to the spec](https://github.com/zarr-developers/zarr-specs/pull/330) have been adopted.
-
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+# zarr-extensions
 
 This repository contains the specifications for Zarr extensions for [Zarr version 3](https://zarr-specs.readthedocs.io/en/latest/v3/core/v3.0.html).