fix spelling of picklable to be in line with the official python

docs

src/ZEO/StorageServer.py

@@ -64,7 +64,7 @@ def log(message, level=logging.INFO, label=None, exc_info=False):
     logger.log(level, message, exc_info=exc_info)
 
 class StorageServerError(StorageError):
-    """Error reported when an unpickleable exception is raised."""
+    """Error reported when an unpicklable exception is raised."""
 
 class ZEOStorage:
     """Proxy to underlying storage for a single remote client."""

src/transaction/interfaces.py

@@ -156,7 +156,7 @@ class ITransaction(zope.interface.Interface):
         """Add extension data to the transaction.
 
         name is the name of the extension property to set, of Python type
-        str; value must be pickleable.  Multiple calls may be made to set
+        str; value must be picklable.  Multiple calls may be made to set
         multiple extension properties, provided the names are distinct.
 
         Storages record the extension data, as meta-data, when a transaction