Document use of URL param "level" for Nodes Stats

[lukas-vlcek]

The Nodes Stats API supports level URL parameter. Possible values are node, indices and shards. In case the value is indices or shards the output contains additional part with relevant data. Check the source code.

I do not think this has been documented, see 5.4 or older 2.4 doc examples.

Is there any interest in documenting this?

[lukas-vlcek]

Thanks @clintongormley