Update web servers X-Robots-Tag header

[wiktor2200]

After upgrading to 25.0.5 or 26 major version, there are warnings about header.
More information could be found here:

• Change X-Robots-Tag header from "none" to "noindex, nofollow" server#36689
• https://help.nextcloud.com/t/x-robots-tag-http-header-not-configured-with-noindex-nofollow-since-nc-26-0-0/158300

There are some more upcoming changes in web server config in 26, so this task is connected with #241 and should be done accordingly.

[aalaesar]

Hello there !
Thank you for the report @wiktor2200
It seems this update can be applied for all versions. So I suppose updating the templates is enough

Ps I also noted in the same discussion the remark about nginx caching for images. I'll check that.

[wiktor2200]

Hi!
Yes, mentioned X-Robots was only one of the changes. I'm going to look through new nginx/apache2 documentation and will
follow-up our jinja template.