Add a changelog entry for v2.2.0

Author: Matt Ferraro

planet_explorer/metadata.txt

@@ -22,6 +22,9 @@ repository=https://github.com/planetlabs/qgis-planet-plugin
 hasProcessingProvider=no
 # Uncomment the following line and add your changelog:
 changelog=
+  v2.2.0 (2022-03-01)
+  * This update adds a new PlanetScope imagery type (PSScene) that includes new 8-band PlanetScope imagery that is radiometrically aligned with Sentinel-2
+  * Users can also find a new option to "harmonize" their PlanetScope Surface Reflectance orders at checkout to improve the radiometric consistency across different PlanetScope sensors
   v2.1.1 (2021-10-01)
   * This patch addresses a number of quality improvements, including a time-stamp discrepancy issue impacting the image search results from the Planet inspector tool, compared to the timestamp on results returned by the image search panel. These time stamps are now consistent and accurate.
   v2.0.1 (2020-05-21)