Fix RST in release notes for 1.5.1

Author: rly

docs/source/hdmf_common_release_notes.rst

@@ -4,7 +4,7 @@ hdmf-common Release Notes
 =========================
 
 1.5.1 (January 10, 2022)
-----------------------
+------------------------
 - No change in the hdmf-common namespace. See :ref:`here <hdmf_experimental_release_notes>` for changes to the
   hdmf-experimental namespace.
 

docs/source/hdmf_experimental_release_notes.rst

@@ -4,7 +4,7 @@ hdmf-experimental Release Notes
 ===============================
 
 0.2.0 (January 10, 2022)
------------------------
+------------------------
 - In the experimental ``ExternalResources``, added ``relative_path`` field to the "objects" table dtype. This is used in
   place of the previous ``field`` field representing the relative path to get to the dataset/attribute from the object.
   The previous ``field`` field will be used to represent a compound type field name if the dataset/attribute is a