Updated KV & Query samples in devguide

Following the creation of the new code-examples infrastructure,

https://github.com/couchbaselabs/sdk-examples/ replacing the old devguide-examples,

and this code generated from <your-docs-repo>/modules/devguide/examples/nodejs 

Please:

• move code samples from howtos/examples to the new dir for the KV & Query pages.
• update the include::s accordingly
• modify the striptags.sh script so that it sends deAntora-ised example files to SDK-examples (instead of devguide, where the pathfinding work sends it).
• Also needed, but not necessary in order to close this ticket, populate https://github.com/couchbaselabs/sdk-examples/tree/master/nodejs  directory with the previous devguide examples, ready to update to 3.0 API.