Update ground_acoustic_absorption.json

Table VI.1 from CNOSSOS reference. I updated the G coefficients.

geoindicators/src/main/resources/org/orbisgis/geoclimate/geoindicators/ground_acoustic_absorption.json

@@ -1,29 +1,29 @@
 {
   "default_g": 0,
   "g": {
-    "asphalt": 0.1,
-    "water": 0.3,
-    "low_vegetation": 1,
+    "asphalt": 0.0,
+    "water": 0.0,
+    "low_vegetation": 0.7,
     "high_vegetation": 1,
     "impervious": 0.1,
     "tree": 1,
     "wood": 1,
     "forest": 1,
     "tree_row": 1,
-    "hedge": 1,
-    "mangrove": 1,
+    "hedge": 0.7,
+    "mangrove": 0.2,
     "orchard": 0.8,
     "banana_plants": 0.8,
     "farmland": 0.7,
     "scrub": 0.7,
-    "grass": 1,
-    "grassland": 1,
-    "heath": 1,
+    "grass": 0.7,
+    "grassland": 0.7,
+    "heath": 0.7,
     "park": 0.7,
-    "meadow": 1,
+    "meadow": 0.7,
     "vineyard": 0.8,
     "sugar_cane": 0.8,
-    "garden": 1,
+    "garden": 0.7,
     "marsh": 0.4,
     "saltmarsh": 0.9
   },