add hdmf common release notes to nwb schema release notes

Author: rly

docs/format/source/format_release_notes.rst

@@ -37,6 +37,9 @@ Release Notes
 
 - Change dims of Image from (y, x) to (x, y). (note: as far as we know, users of NWB 2.0 that use the Image type encode their data as (x, y)) to be consistent with the dimension ordering in ImageSeries.
 
+- Update hdmf-common-schema to version 1.1.0 which includes:
+  - The 'colnames' attribute of ``DynamicTable`` changed from data type 'ascii' to 'text'.
+  - Improved documentation and type docstrings.
 
 2.1.0 (September 2019)
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