[Documentation] Skip AMDA user products access from doctest

GH Actions blocks secrets for pull requests from forks, which makes sense
since it wouldn't be safe. So we can't test user product access from
documentation examples. One improvement would be to find how to skip them
conditionally on PR or when no credentials are available.

Signed-off-by: Alexis Jeandet <alexis.jeandet@member.fsf.org>

docs/user/amda/amda.rst

@@ -165,14 +165,14 @@ Then if you correctly typed your login you should be able to list and get user p
 
     >>> from speasy import amda
     >>> # list user products
-    >>> amda.list_user_parameters()
+    >>> amda.list_user_parameters() # doctest: +SKIP
     [<ParameterIndex: test_param>]
-    >>> amda.list_user_catalogs()
+    >>> amda.list_user_catalogs() # doctest: +SKIP
     [<CatalogIndex: MyCatalog>]
-    >>> amda.list_user_timetables()
+    >>> amda.list_user_timetables() # doctest: +SKIP
     [<TimetableIndex: test_alexis>, <TimetableIndex: test_alexis2>, <TimetableIndex: tt3>]
     >>> # get my first user catalog
-    >>> amda.get_user_catalog(amda.list_user_catalogs()[0])
+    >>> amda.get_user_catalog(amda.list_user_catalogs()[0]) # doctest: +SKIP
     <Catalog: MyCatalog>