fix readme fqdn for doc
</p>
<p align="center">
-:books: <a href="https://docs.crowdsec.net">Documentation</a>
+:books: <a href="https://doc.crowdsec.net">Documentation</a>
:diamond_shape_with_a_dot_inside: <a href="https://hub.crowdsec.net">Hub</a>
:speech_balloon: <a href="https://discourse.crowdsec.net">Discourse </a>
</p>
