Greatly improved DH link list

Moritz Mähr kindly offered to merge his external Digital History link list with our admittedly outdated awesome-dhtools list. He also included Github actions to make the list a member of the awesome lists ecosystem. The much improved list can now be accessed at dh-tech.github.io/awesome-dhtools/

You can help us grow this useful resource by adding your own links to resources and tools via pull requests here. It is of course also possible to advertise your own DH-related tools, corpora, or websites via the awesome list.

We are looking forward to your input!