move to readthedocs

@jrha I updated the script so it recreates exactly what is in https://github.com/quattor/configuration-modules-core/tree/docs
So:
 - removed headers user for jekyll
 - adapted data structure (docs/components/<mdfile>)
 - write mkdocs.yml

should save you some sed time. :)


python best practice recommends writing this as: 
```
with open(..) as fih:
    fih.write(...)
```
and then scoping rules take care of the close()