Add tutorial - Install Uptime-Kuma with Docker and Cloudflare

[DasCanard]

I have read and understood the Contributor's Certificate of Origin available at the end of 
https://raw.githubusercontent.com/hetzneronline/community-content/master/tutorial-template.md
and I hereby certify that I meet the contribution criteria described in it.
Signed-off-by: Richard N. ([email protected])

[DasCanard]

If everything fits, I would then also translate the whole thing into German.

[lars-hubrich]

Please include the following text in this pr to fulfill the contribution guidelines.

I have read and understood the Contributor's Certificate of Origin available at the end of 
https://raw.githubusercontent.com/hetzneronline/community-content/master/tutorial-template.md
and I hereby certify that I meet the contribution criteria described in it.
Signed-off-by: YOUR NAME <[email protected]>

[lars-hubrich]

Periodically fetching the main Hetzner website is probably not the best example.

[DasCanard]

Can i now start working on the german translation?

[lars-hubrich]

I'm just a nerdy Hetzner customer and my approval is just for my recommended changes. @leojakeson is the person who decides which tutorial gets approved.

[DasCanard]

Wow, thanks for this huge contribution to this pull request @svenja11.

I really like the presentation and explanations for the respective steps and I look forward to applying them to the upcoming changes.

I will do my best to implement the changes in a timely manner.

In fact, I probably saved too much on explanations in some places, so thanks again for your contribution. 😄

[svenja11]

@DasCanard Do you still plan to work on this tutorial?

[svenja11]

Closing as there was no activity for a very long time.
If you find time to keep working on this tutorial in future, feel free to open a new pull request @DasCanard.