Deploy nginx configuration for saas-mediawiki

Summary:
This change focus on agora.nasqueron.org and the root configuration
(root = /<title> pages and /index.php entry point).

Reference: https://www.dereckson.be/blog/2013/10/24/mediawiki-nginx-configuration-file/

Ref T845

Test Plan: Browse https://agora.nasqueron.org/status and https://agora.nasqueron.org/

Reviewers: dereckson

Reviewed By: dereckson

Maniphest Tasks: T845

Differential Revision: https://devcentral.nasqueron.org/D1457