Revival of #1738.

Could you consider adding an option to serve hidden static files and templates? I cannot see any reason why one wouldn't want to serve these hidden files, and in particular the .well-known directory is used for a lot of things that one could want in their documentation, including:

• ACME challenges (for Let's Encrypt)
• security.txt
• Keybase Site Verification
• Do-Not-Track policies
• HTTPS Opportunistic Encryption

see https://www.iana.org/assignments/well-known-uris/well-known-uris.xhtml

It would be very useful to have this as a built-in option. A plugin, which could work around this, seems completely unnecessary. Could you explain why this is not enabled, and reconsider the behaviour, or at least add an exception for the well standardised .well-known directory? Or is there a good reason I'm missing not to do this?