* docs: update chat example and add info to its readme
* docs: update echo example
* docs: update libp2p in browser example
* docs: update pubsub example
* docs: update peer and content routing examples
* docs: update discovery mechanisms example
* docs: update encrypted comms example
* docs: update protocol and stream muxing example
* feat: add config validation
* test: update CI configs, use only node 8
