* update tailscale.md to reflect best-practices
The provided -Syy is supposed to be used to redownload all package databases,
while the command chain itself is a partial upgrade which is not recommended
either for rolling release distributions.
Replace the full database redownload with a database update and run a system
upgrade while installing tailscaled.
* remove unnecessary sync command from video.md
* remove unnecessary sync command from bluetooth_hid.md
* remove unnecessary sync command from arduino_hid.md
* update faq.md to reflect best practices
* update letsencrypt.md to keep system up-to-date when installing packages
