Add brief release notes for 5.6.0 release

Author: lesserwhirls

docs/src/site/pages/netcdfJava/Upgrade.md

@@ -21,13 +21,23 @@ Java WebStart has been deprecated as of [Java 9](https://www.oracle.com/technetw
 As such, we no longer utilize WebStart.
 
 ## Quick Navigation
+* [Summary of changes for v5.6.x](#netcdf-java-api-changes-56x)
 * [Summary of changes for v5.5.x](#netcdf-java-api-changes-55x)
 * [Summary of changes for v5.4.x](#netcdf-java-api-changes-54x)
 * [Summary of changes for v5.3.x](#netcdf-java-api-changes-53x)
 * [Summary of changes for v5.2.x](#netcdf-java-api-changes-52x)
 * [Summary of changes for v5.1.x](#netcdf-java-api-changes-51x)
 * [Summary of changes for v5.0.x](#netcdf-java-api-changes-50x)
 
+## netCDF-Java API Changes (5.6.x)
+
+Point release notes:
+* [5.6.0](https://github.com/Unidata/netcdf-java/releases/tag/v5.6.0){:target="_blank"} (_2024-07-16_)
+
+5.6.x contains significant improvements to DAP4, Zarr, and Sigmet IOSP support.
+Zarr support includes a new API for the Filters package.
+Two new pre-processing modules are now available as NcML enhancements: Standardize and Normalize.
+
 ## netCDF-Java API Changes (5.5.x)
 
 Point release notes: