Add 10m Annual Land Cover update to CHANGELOG (#319)

Author: lossyrob

docs/overview/changelog.md

@@ -53,6 +53,7 @@ This release includes many new datasets. Each of these links to the dataset deta
   * [USGS 3DEP Lidar Intensity](https://planetarycomputer.microsoft.com/dataset/3dep-lidar-intensity)
   * [USGS 3DEP Lidar Returns](https://planetarycomputer.microsoft.com/dataset/3dep-lidar-returns)
 * [NAIP](https://planetarycomputer.microsoft.com/dataset/naip): National Agriculture Imagery Program (NAIP) imagery updated for 2020
+* [10m Annual Land Use Land Cover](https://planetarycomputer.microsoft.com/dataset/io-lulc-9-class): Added data for 2020 and 2021 from model output generated by [Impact Observatory](http://impactobservatory.com/)
 * [CIL Global Downscaled Projections for Climate Impacts Research Collection](https://planetarycomputer.microsoft.com/dataset/group/cil-gdpcir): Climate Impact Lab Global Downscaled Projections for Climate Impacts Research
 * [ECMWF Open Data (real-time)](https://planetarycomputer.microsoft.com/dataset/ecmwf-forecast): ECMWF Open Data (Real Time) forecasts
 * [ERA5 - PDS](https://planetarycomputer.microsoft.com/dataset/era5-pds): A comprehensive reanalysis, which assimilates as many observations as possible in the upper air and near surface.