Document correct BoM usage

[ppalaga]

Issues like #2131 are a clear sign that we are lacking on documentation about dependency management. Let me file a new issue for that.

We should document at least:

• The easiest and most straightforward option is to use https://code.quarkus.io/ producing a project with the quarkus-universe-bom that aggregates camel-quarkus-bom. This has the advantage that the user does not need to care for the compatibility of the individual artifacts that may potentially come from various independent project. All artifacts managed by quarkus-universe-bom are supposed to work together flawlessly.
• Using camel-quarkus-bom instead of quarkus-universe-bom: As long as the user does not import any other BoM beyond camel-quarkus-bom, this is an easy and reliable option too. camel-quarkus-bom manages all supported Camel artifacts and it also imports quarkus-bom. This option can be used if the user plans to use only extensions from Quarkus and Camel Quarkus.
• Combinig camel-quarkus-bom or quarkus-universe-bom with each other manually: take care that you combine compatible versions. camel-quarkus-bom should typically be imported before quarkus-universe-bom - see the next point.
• Combinig camel-quarkus-bom with any other BoM: think carefully in which order you import them. The order of imports makes up the precedence. This matters for the artifacts managed by both BoMs.