i18n(de): tutorial final fixes and improvements (for now)

[trueberryless]

Description

I never noticed the suggestions from @randomguy-2650 in the de/tutorial PR (#12502), sorry for that...

Now I made this PR that fixes all suggestions in the whole tutorial.
One question: Do you think I should append a . to all pre-check elements? I'm not sure if lists should have a dot at the end when they form a whole sentence...

Requesting review from @louisescher and @randomguy-2650 again.

[astrobot-houston]

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Tracked Files

File	Note
de/tutorial/1-setup/1.mdx	Localization changed, will be marked as complete.
de/tutorial/1-setup/2.mdx	Localization changed, will be marked as complete.
de/tutorial/1-setup/3.mdx	Localization changed, will be marked as complete.
de/tutorial/1-setup/4.mdx	Localization changed, will be marked as complete.
de/tutorial/1-setup/5.mdx	Localization changed, will be marked as complete.
de/tutorial/1-setup/index.mdx	Localization changed, will be marked as complete.
de/tutorial/2-pages/1.mdx	Localization changed, will be marked as complete.
de/tutorial/2-pages/2.mdx	Localization changed, will be marked as complete.
de/tutorial/2-pages/3.mdx	Localization changed, will be marked as complete.
de/tutorial/2-pages/4.mdx	Localization changed, will be marked as complete.
de/tutorial/2-pages/5.mdx	Localization changed, will be marked as complete.
de/tutorial/2-pages/index.mdx	Localization changed, will be marked as complete.
de/tutorial/3-components/1.mdx	Localization changed, will be marked as complete.
de/tutorial/3-components/2.mdx	Localization changed, will be marked as complete.
de/tutorial/3-components/3.mdx	Localization changed, will be marked as complete.
de/tutorial/3-components/4.mdx	Localization changed, will be marked as complete.
de/tutorial/3-components/index.mdx	Localization changed, will be marked as complete.
de/tutorial/4-layouts/1.mdx	Localization changed, will be marked as complete.
de/tutorial/4-layouts/2.mdx	Localization changed, will be marked as complete.
de/tutorial/4-layouts/3.mdx	Localization changed, will be marked as complete.
de/tutorial/5-astro-api/1.mdx	Localization changed, will be marked as complete.
de/tutorial/5-astro-api/2.mdx	Localization changed, will be marked as complete.
de/tutorial/5-astro-api/3.mdx	Localization changed, will be marked as complete.
de/tutorial/5-astro-api/4.mdx	Localization changed, will be marked as complete.
de/tutorial/5-astro-api/index.mdx	Localization changed, will be marked as complete.
de/tutorial/6-islands/1.mdx	Localization changed, will be marked as complete.
de/tutorial/6-islands/2.mdx	Localization changed, will be marked as complete.
de/tutorial/6-islands/4.mdx	Localization changed, will be marked as complete.

Warnings reference

Icon	Description
🔄️	The source for this localization has been updated since the creation of this pull request, make sure all changes in the source have been applied.

[yanthomasdev]

Nice work!