Deactivate Milestone links for artifacts which don't have milestone versions

[pderop]

When doing the 2022.0.9 / 2023.0.0-M1 / 2020.0.34 releases, there are some issues with the projectreactor site:

For the 2023.0.0-M1 milestone version, only the Reactor Core and the Reactor Test should have some Milestone links, and other artifacts (like Reactor Netty, Reactor Pool) should not have such links, because only Reactor Core/Test are part of the 2023.0.0-M1.

For example, when we browse the site, the Milestone links are enabled for the following artifact:

• reactor extra (Javadoc with milestone 3.5.0-RC1)
• reactor netty (Javadoc and Reference with milestone 1.1.0-RC1)
• reactor adapter (Javadoc with milestone 3.5.0-RC1)
• reactor kotling extensions (Javadoc with milestone 1.2.0-RC1)
• reactor-pool (Javadoc with milestone 1.0.0-RC1)

This PR is an attempt to fix the problems with two fixes which allow to hide artifacts Milestone links for the components which are not part of the 2023.0.0-M1 milestone:

1. first fix in boms.yml, where the artifacts which are not part of the 2023.0.0-M1 are commented

2. annother fix is in docs.html, where the Reactor Netty Milestone link for the Reference is included even if it commented in the bom.yml (there is a wrong test which is testing milestone.testVersion instead of milestone. nettyVersion).

Without this PR, currently, for example we have the Milestone links that are appearing for Reactor Netty and Reactor Adapter:

and with the proposed PR, the Milestone links are not displayed anymore:

Admittedly, maybe there is still a problem, because the Reactor Netty and Reactor Adapter release trains don't contain anymore the 2023.0.0-M1 version ...

[pderop]

@reactor/core-team , can you take a look again please ?

In the last commit:

• all release trains are now displayed for a given module version. The predicate used to decide if the Milestone button is displayed is based on the module version found from the milestone module version in the boms.yml: if the version ends with -M<digit number>, then the Milestone button is displayed, else it is not.

• Also, added missing rabbitVersion in boms.yml.

Example:

Thanks.