Add locations for nginx config that should be denied for security reasons

[smueller18]

As mentioned in https://pydio.com/de/docs/kb/system/installing-debiannginx, the nginx config should include a deny for some paths for security reasons. Add this part in the config sample, because it is a must-have to protect the Pydio installation and nobody using nginx forget it.

[cdujeu]

hi @smueller18 I totally agree, still I need you to sign the CLA so that I can merge the PR. Can you do that quickly ? Thanks! See https://pydio.com/fr/community/contribute/contributor-license-agreement-cla

[smueller18]

Done