Improve wording in Getting Started and other tutorials (backport #405)

[mergify]

This is an automatic backport of pull request #405 done by Mergify.
Cherry-pick of d71d784 has failed:

On branch mergify/bp/humble/pr-405
Your branch is up to date with 'origin/humble'.

You are currently cherry-picking commit d71d784.
  (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)

Changes to be committed:
	modified:   doc/how_to_contribute/how_to_write_tutorials.rst
	modified:   doc/tutorials/getting_started/getting_started.rst
	modified:   doc/tutorials/quickstart_in_rviz/quickstart_in_rviz_tutorial.rst
	modified:   doc/tutorials/visualizing_in_rviz/visualizing_in_rviz.rst
	modified:   doc/tutorials/your_first_project/your_first_project.rst

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

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

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