DOC: What is pfun?

[MartinThoma]

Is it a Python environment (like cpython)? Is it a linter (like mypy / pylint / flake8)? Is it a learning project?

Who should use it? In which context is it useful? Why was it created? Are there similar projects?

[suned]

I've added an introductory snippet to the readme and frontpage of the docs in #68, as well as a list of similar projects. Do you think that would have helped you?

I don't think it makes sense to go into details about what functional programming is and why its useful in the documentation, I think that would simply be too much information in one place. Ive linked to the articles I've written on those subjects in both the readme and docs, and there is a lot of excellent information elsewhere on those topics.

[suned]

Added a "what is this?" section to the documentation.