docs: describe how to use the silent flag for dependencies (#680)

docs/static/schema.json

@@ -241,6 +241,10 @@
           "vars": {
             "description": "Values passed to the task called",
             "$ref": "#/definitions/3/vars"
+          },
+          "silent": {
+            "description": "Hides task name and command from output. The command's output will still be redirected to `STDOUT` and `STDERR`.",
+            "type": "boolean"
           }
         }
       },