Add notice to the ROS 2 and RTI Connext documentation

[fgallegosalido]

Description

Add notice about official ROS 2 and RTI Connext documentation to the README.

Is this user-facing behavior change?

Users will now have a direct link to the official ROS 2 and RTI Connext documentation in the README, with the most up-to-date information.

Did you use Generative AI?

No

Additional Information

[fgallegosalido]

This pull request needs to be reviewed by @rkorte and @lloadholt before merging.

[fgallegosalido]

@fujitatomoya can you review this? Also, can we backport this to Lyrical and Kilted?

[ahcorde]

https://github.com/Mergifyio backport lyrical kilted

[mergify]

backport lyrical kilted

✅ Backports have been created

Details

• #228 Add notice to the ROS 2 and RTI Connext documentation (backport #227) has been created for branch lyrical
• #229 Add notice to the ROS 2 and RTI Connext documentation (backport #227) has been created for branch kilted but encountered conflicts

Cherry-pick of 3dbef7c has failed:

On branch mergify/bp/kilted/pr-227
Your branch is up to date with 'origin/kilted'.

You are currently cherry-picking commit 3dbef7c.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   README.md

no changes added to commit (use "git add" and/or "git commit -a")

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally