Clarify purpose of this driver vs. generic PostgreSQL driver

[amotl]

Hi there,

this driver is clearly to consume CrateDB's HTTP API, this should be reflected better within the README document. I think it still has purpose, providing some highlevel DDL-related API methods, as well as a wrapper interface around BLOB tables.

On the other hand, we may want to advise the community to use a generic PostgreSQL driver for regular use with Ruby. Can you recommend a corresponding driver, @hammerhead? Would ruby-pg be the right choice?

See also:

• Check if CrateDB ActiveRecord adapter can be used with ruby-pg instead of crate_ruby activerecord-crate-adapter#19

With kind regards,
Andreas.

/cc @seut