Add API reference for V3 Implementation in the docs

docs/api.rst

@@ -13,6 +13,7 @@ API reference
     api/codecs
     api/attrs
     api/sync
+    api/v3
 
 Indices and tables
 ------------------

docs/api/v3.rst

@@ -0,0 +1,77 @@
+V3 Specification Implementation(``zarr._storage.v3``)
+=====================================================
+
+This module contains the implementation of the `Zarr V3 Specification <https://zarr-specs.readthedocs.io/en/latest/core/v3.0.html#zarr-core-specification-v3-0>`_.
+
+.. warning::
+    Since Zarr Python 2.12 release, this module provides experimental infrastructure for reading and
+    writing the upcoming V3 spec of the Zarr format. Users wishing to prepare for the migration can set
+    the environment variable ``ZARR_V3_EXPERIMENTAL_API=1`` to begin experimenting, however data
+    written with this API should be expected to become stale, as the implementation will still change.
+
+The new ``zarr._store.v3`` package has the necessary classes and functions for evaluating Zarr V3.
+Since the design is not finalised, the classes and functions are not automatically imported into
+the regular Zarr namespace.
+
+Code snippet for creating Zarr V3 arrays::
+
+	>>> import zarr
+	>>> z = zarr.create((10000, 10000),
+	>>>		chunks=(100, 100),
+	>>>		dtype='f8',
+	>>>		compressor='default',
+	>>>		path='path-where-you-want-zarr-v3-array',
+	>>>		zarr_version=3)
+
+Further, you can use `z.info` to see details about the array you just created::
+
+	>>> z.info
+	Name               : path-where-you-want-zarr-v3-array
+	Type               : zarr.core.Array
+	Data type          : float64
+	Shape              : (10000, 10000)
+	Chunk shape        : (100, 100)
+	Order              : C
+	Read-only          : False
+	Compressor         : Blosc(cname='lz4', clevel=5, shuffle=SHUFFLE, blocksize=0)
+	Store type         : zarr._storage.v3.KVStoreV3
+	No. bytes          : 800000000 (762.9M)
+	No. bytes stored   : 557
+	Storage ratio      : 1436265.7
+	Chunks initialized : 0/10000
+
+You can also check ``Store type`` here (which indicates Zarr V3).
+
+.. module:: zarr._storage.v3
+
+.. autoclass:: RmdirV3
+.. autoclass:: KVStoreV3
+.. autoclass:: FSStoreV3
+.. autoclass:: MemoryStoreV3
+.. autoclass:: DirectoryStoreV3
+.. autoclass:: ZipStoreV3
+.. autoclass:: RedisStoreV3
+.. autoclass:: MongoDBStoreV3
+.. autoclass:: DBMStoreV3
+.. autoclass:: LMDBStoreV3
+.. autoclass:: SQLiteStoreV3
+.. autoclass:: LRUStoreCacheV3
+.. autoclass:: ConsolidatedMetadataStoreV3
+
+In v3 `storage transformers <https://zarr-specs.readthedocs.io/en/latest/core/v3.0.html#id19>`_
+can be set via ``zarr.create(…, storage_transformers=[…])``.
+The experimental sharding storage transformer can be tested by setting
+the environment variable ``ZARR_V3_SHARDING=1``. Data written with this flag
+enabled should be expected to become stale until
+`ZEP 2 <https://zarr.dev/zeps/draft/ZEP0002.html>`_ is approved
+and fully implemented.
+
+.. module:: zarr._storage.v3_storage_transformers
+
+.. autoclass:: ShardingStorageTransformer
+
+The abstract base class for storage transformers is
+
+.. module:: zarr._storage.store
+
+.. autoclass:: StorageTransformer