move documentation from wiki to /docs folder

[mrothauer]

the master branch can be configured to show content of /docs folder automatically on
http://foodcoopshop.github.io/foodcoopshop

how this works is described here:
https://help.github.com/articles/user-organization-and-project-pages/

reason for the change is that users need to be granted write permissions to be able to change wiki pages. if the documentation is moved to /docs, pull requests can be done by anyone by creating a pull request from a fork

another reason is the increased flexibility (eg. integration of new languages, make a dynamic table of contents...

tasks

• check if wiki pages can contain redirects (or at least copy a link to the new url)
• move content to /docs folder
• replace links to wiki in source code
• use jekyll for building the docs: https://help.github.com/articles/using-jekyll-as-a-static-site-generator-with-github-pages/

question

• as the master branch's /docs folder is taken for the build of the gh pages url, how to view changes on develop branch? maybe it's enough to view the code, but there will be no built version of the docs

[mrothauer]

the new documentation can be found here: https://foodcoopshop.github.io/. it's mobile friendly and the implementation is a good solution for the demands of foodcoopshop. the source code can be found in an own repository (https://github.com/foodcoopshop/foodcoopshop.github.io) where future devs or maintainers can update via pull request.