Fix typo in getting started C++ section (backport #1002)

[mergify]

Description

This PR deletes the section 1.3.6.1 in FastDDS, which was made unnecessary after an update on the CMakeLists.txt and referred to the wrong code afterwards.

@Mergifyio backport 3.1.x 3.0.x 2.14.x

Contributor Checklist

• Commit messages follow the project guidelines.
• N/A Code snippets related to the added documentation have been provided.
• Documentation tests pass locally.
• Applicable backports have been included in the description.

Reviewer Checklist

• The PR has a milestone assigned.
• The title and description correctly express the PR's purpose.
• Check contributor checklist is correct.
• CI passes without warnings or errors.

---

This is an automatic backport of pull request #1002 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 5815f2d has failed:

On branch mergify/bp/2.14.x/pr-1002
Your branch is up to date with 'origin/2.14.x'.

You are currently cherry-picking commit 5815f2d.
  (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:   docs/fastdds/getting_started/simple_app/includes/dataType.rst

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

[juanjo4936]

LGTM