Docs: Consider relocating access tip

[bmunkholm]

In PR #889, below tip was removed:

If you access port 4200 via a client library or command-line tool like curl or wget, the request will be handled by the CrateDB Rest API_, and the response will be in JSON.

Consider where that could be relevant to relocate. Perhaps: Guide/Connectivity Guide/How to connect Reference/Client Interfaces

[amotl]

Hi. This comment was only directed to the scope of GH-889. In general, across cratedb-guide, there is knowledge about CrateDB listening on port 4200, so I think it doesn't have to be repeated.