correcting metadata

Author: justbia

exploring-surface-albedo.ipynb

@@ -1226,9 +1226,7 @@
     "satellite": "",
     "sensor": "",
     "service": "",
-    "subtheme": [
-     "Climate system monitoring - Terrestrial"
-    ],
+    "subtheme": "Climate system monitoring - Terrestrial",
     "theme": "Climate",
     "variable": [
      "Broadband directional surface albedo",