don't render WmsTimeDimension example

Author: Conengmo

docs/user_guide/plugins/WmsTimeDimension.md

@@ -1,18 +1,13 @@
-```{code-cell} ipython3
----
-nbsphinx: hidden
----
-import folium
-import folium.plugins
-```
-
 # TimestampedWmsTileLayers
 
 Add a time dimension to a WMS tile layer.
 
+Note that we don't render the output in this example, because the web service
+used here is not always available.
+
 ### Exploring the WMS with OWSLib
 
-```{code-cell} ipython3
+```
 from owslib.wms import WebMapService
 
 
@@ -25,7 +20,7 @@ print("\n".join(web_map_services.contents.keys()))
 
 ### Layer metadata
 
-```{code-cell} ipython3
+```
 layer = "CRW_SST"
 wms = web_map_services.contents[layer]
 
@@ -46,7 +41,7 @@ if style not in wms.styles:
 
 ### Map with WmsTileLayer and TimestampedWmsTileLayers
 
-```{code-cell} ipython3
+```
 m = folium.Map(location=[-40, -50], zoom_start=5)
 
 wms_tile_layer = folium.WmsTileLayer(