Fix error in Schema family docs

Update portion of Grid Schema transaction family docs to reflect the
correct hash algorithm for addressing. This makes this section
accurate and consistent with the rest of the doc.

Signed-off-by: Davey Newhall <[email protected]>

Author: dnewh

docs/source/transaction_family_specifications/grid_schema_family_specification.rst

@@ -481,7 +481,7 @@ Addressing
 
 Grid Schemas are stored under the Grid namespace ``621dee``. For each schemas,
 the address is formed by concatenating the namespace, the special policy
-namespace of ``01``, and the first 62 characters of the SHA-256 hash of the
+namespace of ``01``, and the first 62 characters of the SHA-512 hash of the
 schema name.
 
 For example, the address of the ``Lightbulb`` schema defined in the example