Revert "Allow epub, pdf downloads (solves #52)"

This reverts commit e57796b.

Author: hcartiaux

.readthedocs.yaml

@@ -11,10 +11,6 @@ build:
 mkdocs:
   configuration: mkdocs.yml
 
-formats:
-  - epub
-  - pdf
-
 python:
   install:
   - requirements: requirements.txt