German Translation for html-css-beginners Workshop with proper branch names

As stated in closed Pullrequest #27 before, here another pull request with corrected branch targets. Original message below:
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Hello there!

We, the OTS Dortmund chapter, have been in need to have the short version of the html/css workshop in german language. Therefore we translated the documents. Now we want to share them with the community.

I hope you like our contribution and accept our pull request soon. :)

Thank you and take care,
Dennis