Add en test

1 job for main in 2 minutes and 23 seconds (queued for 2 seconds)
Name Stage Failure
pages Deploy
info: installing plugin "katex-plus" 
info: install plugin "katex-plus" (*) from NPM with version 1.1.0
info: >> plugin "katex-plus" installed with success
$ gitbook build . public
info: parsing multilingual book, with 2 languages

FileNotFoundError: No "README" file (or is ignored)
Cleaning up project directory and file based variables
ERROR: Job failed: exit code 1