Change the header for logout curl

Change -H 'Content-Type: application/octet-stream' on -H 'Content-Type: application/x-www-form-urlencoded' in Logout
to keep consistency with other curls in Authentication section of API docs.

• current LOGOUT: $ curl 'https://minerva-dev.lcsb.uni.lu/minerva/api/doLogout' -X POST \ --cookie 'MINERVA_AUTH_TOKEN=xxxxxxxx' \ -H 'Content-Type: application/octet-stream'