Node.js SDK 2.x: Explain how to use rawParam to add request level parameters to a N1QL query

It is possible through the "rawParam" method to pass in request level parameters when doing N1QL queries https://docs.couchbase.com/server/current/settings/query-settings.html#section_nnj_sjk_k1b

We should explain how to use it, for example for things like clientContextId:

var q = N1qlQuery.fromString('query string here');

q.rawParam('client_context_id', 'Some value');

var req = bucket.query(q);

This feature seems to have been added in the 2.6.0 version, so it should only apply to 2.6 and higher.