redis.adoc: Document how to access binary data using MutinyRedis.
redis.adoc: Document how to access binary data using MutinyRedis.

Since RedisClient and ReactiveRedisClient, like vertx-redis-client's
RedisAPI, only operate on UTF-8-encoded strings, efficiently handling
binary data requires the use of the lower-level MutinyRedis
(corresponding to vertx-redis-client's Redis class).

This change documents how to do this.

quarkusio/quarkus,quarkusio/quarkus,quarkusio/quarkus,quarkusio/quarkus,quarkusio/quarkus