add change notes to spec

Author: alimanfoo

docs/spec/v2.rst

@@ -466,9 +466,29 @@ What has been stored::
 Changes
 -------
 
+Version 2 clarifications
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+The following changes have been made to the version 2 specification since it was
+initially published to clarify ambiguities and add some missing information.
+
+* The specification now describes how bytes fill values should be encoded and
+  decoded for arrays with a fixed-length byte string data type (:issue:`165`,
+  :issue:`176`).
+
+* The specification now clarifies that datetime64 and timedelta64 data types are not
+  supported in this version (:issue:`85`).
+
+* The specification now clarifies that the '.zattrs' key does not have to be present for
+  either arrays or groups, and if absent then custom attributes should be treated as
+  empty.
+
+
 Changes in version 2
 ~~~~~~~~~~~~~~~~~~~~
 
+The following changes were made between version 1 and version 2 of this specification:
+
 * Added support for storing multiple arrays in the same store and organising
   arrays into hierarchies using groups.
 * Array metadata is now stored under the ".zarray" key instead of the "meta"

zarr/storage.py

@@ -1472,7 +1472,9 @@ def _lmdb_decode_key_bytes(key):
 
 
 class LMDBStore(MutableMapping):
-    """Storage class using LMDB.
+    """Storage class using LMDB. Requires the `lmdb <http://lmdb.readthedocs.io/>`_
+    package to be installed.
+
 
     Parameters
     ----------
@@ -1484,10 +1486,6 @@ class LMDBStore(MutableMapping):
     **kwargs
         Keyword arguments passed through to the `lmdb.open` function.
 
-    Notes
-    -----
-    Requires the `lmdb <http://lmdb.readthedocs.io/>`_ package to be installed.
-
     Examples
     --------
     Store a single array::