Add "wetterdienst about coverage" to cli.py (earthobservations#151)

This invokes "discover_climate_observations".

.flake8

@@ -2,4 +2,4 @@
 select = B,B9,BLK,C,E,F,W,S
 ignore = E203,W503
 max-line-length = 88
-per-file-ignores = tests/*:S101, wetterdienst/__init__.py:F401
+per-file-ignores = tests/*:S101, wetterdienst/__init__.py:F401 wetterdienst/cli.py:B950

wetterdienst/cli.py

@@ -12,6 +12,7 @@
     __version__,
     metadata_for_climate_observations,
     get_nearby_stations,
+    discover_climate_observations,
 )
 from wetterdienst.additionals.geo_location import stations_to_geojson
 from wetterdienst.additionals.time_handling import mktimerange, parse_datetime
@@ -32,6 +33,7 @@ def run():
       wetterdienst readings --parameter=<parameter> --resolution=<resolution> --period=<period> --station=<station> [--persist] [--date=<date>] [--format=<format>]  # noqa:E501
       wetterdienst readings --parameter=<parameter> --resolution=<resolution> --period=<period> --latitude= --longitude= [--count=] [--distance=] [--persist] [--date=<date>] [--format=<format>]  # noqa:E501
       wetterdienst about [parameters] [resolutions] [periods]
+      wetterdienst about coverage [--parameter=<parameter>] [--resolution=<resolution>] [--period=<period>]
       wetterdienst --version
       wetterdienst (-h | --help)
 
@@ -313,6 +315,15 @@ def output(thing):
     elif options.periods:
         output(PeriodType)
 
+    elif options.coverage:
+        print(
+            discover_climate_observations(
+                time_resolution=options.resolution,
+                parameter=read_list(options.parameter),
+                period_type=read_list(options.period),
+            )
+        )
+
     else:
         log.error(
             'Invoke "wetterdienst about" with one of "parameters", "resolutions" or '