Stop using the dd.dataset.description field and replace it with colle…

…ction.description

staged html :
https://developers.devsite.corp.google.com/earth-engine/datasets/catalog/MODIS_061_MOD10A1#description

https://developers.devsite.corp.google.com/earth-engine/datasets/catalog/COPERNICUS_S5P_OFFL_L3_O3

PiperOrigin-RevId: 711401894

stac/stac_lib.py

@@ -406,6 +406,12 @@ def public_id(self) -> str:
   def title(self) -> str:
     return self.stac_json['title']
 
+  def description(self) -> str:
+    if 'description' in self.stac_json:
+      description = self.stac_json['description']
+      return description
+    return ''
+
   def dataset_type(self) -> stac_checker.GeeType:
     return stac_checker.GeeType(self.stac_json['gee:type'])