Using DNS SRV records Documentation

We can possibly improve upon our documentation for Using DNS SRV records. Right now, if the user is not fully familiar with SRV records it can potentially be confusing as it is a very high level documentation on what's needed.

For example, the documentation does not detail where to use _couchbase._tcp.<hostname> (whether in SRV records, A records, in connection string), why that is needed and what can happen if the user uses something else.

In general, it would be great to have an easy step by step guide on how to create SRV records and A records, how they should look like when seen through nslookup and finally how to identify what to use in the connection string. We can also possibly add some troubleshooting tips too.