Reflect repo ownership change in README and help.

[evanberkowitz]

Repo ownership moves the documentation, etc.

I just grepped for jl-wynen and replaced, so I think I got it all but I couldn't swear to it.

[jl-wynen]

• Consider updating the license to 2021 and @evanberkowitz:
  

  isle/LICENSE

  Line 3 in 235dae0

  Copyright (c) 2018 Jan-Lukas Wynen

• Similarly, the author and author_email fields of the package should probably be changed, too:
  

  isle/setup.py

  Line 43 in 5f183fb

  author="Jan-Lukas Wynen",

• Change jl-wynen.github.io/isle/ to evanberkowitz.github.io/isle/ on the repo description on GitHub.

• Lastly, are GitHub Actions set up correctly? Not related to this PR, but they don't trigger on pull requests. So you'll have to make some changes to devel to see if it works.

[jl-wynen]

Please check my previous comment.