Sphinx documentation
The existing readmes in Allen have been ported to reStructured text format and now populate a Sphinx documentation web page: https://allen-doc.docs.cern.ch/index.html
Some tasks in #228 are still outstanding and can be added in subsequent MRs. But I propose to merge this MR with the currently existing configuration and content, so that many authors can help completing the documentation.
Edited by Dorothea Vom Bruch