Add a link to the Spring Boot docs about Redis configuration.

[Buzzardo]

As the discussion in #20 indicates, it would be good to add a link to the Spring Boot docs that have to do with Redis configuration.

This is a good one for a first-time committer.

[zhangwt-cn]

Hello, I want to try to complete this work, but I don't know where this document needs to be added to this project.

[Buzzardo]

I would add it as a note at the top of the "Create a Redis Message Receiver" section.

[zhangwt-cn]

@Buzzardo I've done it, please help review it #27

[robertmcnees]

In the PR #32 I added the link specified in #20. The guide now uses Spring Boot Docker Compose support, so using application.properties to configure connection details is no longer required, if it ever was. I dropped the link in the NOTE section, so hopefully readers will be able to easily find more information if they choose.