Documentation update. (#1654)

- Unifying `name_de` description for `mountain_peak` layer.
- Update the version of PostGIS for `generate-sqltomvt` function.

layers/mountain_peak/mountain_peak.yaml

@@ -10,7 +10,7 @@ layer:
   fields:
     name: The OSM [`name`](http://wiki.openstreetmap.org/wiki/Key:name) value of the peak. Language-specific values are in `name:xx`.
     name_en: English name `name:en` if available, otherwise `name`. This is deprecated and will be removed in a future release in favor of `name:en`.
-    name_de: German name `name:de` if available, otherwise `name` or `name:en`.
+    name_de: German name `name:de` if available, otherwise `name` or `name:en`. This is deprecated and will be removed in a future release in favor of `name:de`.
     class:
       description: |
         Use the **class** to differentiate between natural objects.