update nginx documentation

[arkmoon]

Changes:

• Removed trailing spaces
• Fixed wrong directory name from 'enabled-sites' to 'sites-available' (sites-available/default symlinks to sites-enabled/default out of the box)
• Changed order of certificate editing as it appears in order on cloudflare's certificate generator page

[kristjank]

Thanks. Could you please also update changes on docs.ark.io / as this will be the main point for documentation, and most of docs from here were moved there.

There you have a similar feature - suggest edits in the top right corner.

[arkmoon]

I'm not seeing the fail2ban documentation on this page on docs.ark.io, was that removed?
I proposed my edits there for everything else.

[kristjank]

You can add the section. Looks like lost. Or add subpage. Tnx for checking