Recommend dependency version management tooling based on use case

Similar to the problem in https://github.com/pypa/python-packaging-user-guide/issues/118 with regards to virtual environment management, our current tooling recommendations don't provide a pointer to higher level dependency version management tools like pipenv or pip-tools, they only refer to pip itself.

While we don't want to overwhelm people with choice, I think we're currently doing folks a disservice by letting them think pip is all there is, rather than guiding them towards more opinionated higher level tooling:

• pipenv: web application development (and potentially other forms of application development)
• pip-tools: general application development (useful when pipenv doesn't align with your needs)
• conda: language-independent cross-platform package (useful when you have extensive external dependencies)

Beginne damit, die aktuellen Empfehlungen für Tools und das zugehörige Issue 118 von python-packaging-user-guide zu lesen. Ermittle, wo pip derzeit vorgestellt wird, und aktualisiere diese Dokumentation, um Leser je nach Anwendungsfall zu pipenv, pip-tools oder conda zu führen. Erledigt ist die Aufgabe, wenn die Empfehlungen klar sind, ohne die Leser mit unnötigen Auswahlmöglichkeiten zu überfordern.