v.in.wfs manual: fix example (#809)

replace now broken example (server unavailable) to Copernicus Sentinel-2 satellite scene footprints

scripts/v.in.wfs/v.in.wfs.html

@@ -5,17 +5,18 @@ external servers.
 
 <h2>EXAMPLES</h2>
 
-Import of world cities with population &gt; 1 million:
+<h3>WFS import without credentials</h3>
+Import of Copernicus Sentinel-2 satellite scene footprints:
+
 <p>
 <div class="code"><pre>
 # run in Latitude-Longitude location (EPGS code 4326):
-# download geonam_gt1M layer:
-v.in.wfs \
-  url="http://mapserver.flightgear.org/ms?Service=WFS&amp;request=GetFeature&amp;version=1.0.0" \
-  name=geonam_gt1M output=geonam_gt1M
+# download "sentinel:mgrs" layer:
+v.in.wfs url="https://geoserver.mundialis.de/geoserver/sentinel/wfs?" name="sentinel:mgrs" output=sentinel2_mgrs
 </pre></div>
 
-<p>
+<h3>WFS import with API key</h3>
+
 Download 25 ship wrecks from LINZ data service:
 <br>
 (first create yourself a free API key at
@@ -26,7 +27,7 @@ Download 25 ship wrecks from LINZ data service:
 # run in LatLong location:
 URL='http://wfs.data.linz.govt.nz/&lt;PUT YOUR API KEY HERE&gt;/wfs?'
 
-# download available layers to wms_capabilities.xml
+# download list of available layers to wms_capabilities.xml
 v.in.wfs -l url="$URL" 
 </pre></div>
 
@@ -47,6 +48,7 @@ Parser support (for GML).
 <em>
 <a href="g.region.html">g.region</a>,
 <a href="r.in.wms.html">r.in.wms</a>,
+<a href="v.import.html">v.import</a>,
 <a href="v.in.ogr.html">v.in.ogr</a>
 </em>