Remove number_of_shards setting from clone API example (#5073)

This setting is allowed only if the number of shards matches that of
the source index, and that's the behaviour anyway, so it is needlessly
confusing to include it here.

Author: PeteGillinElastic

output/openapi/elasticsearch-openapi.json

@@ -8,7 +8,7 @@ value: "{
 
   \  \"settings\": {
 
-  \    \"index.number_of_shards\": 5
+  \    \"index.refresh_interval\": \"2s\"
 
   \  },