[1.1.1.1] Add steps to allow DNS over TLS for systemd-resolved (#18617)

* Changed value for resolved to allow DNS over TLS for systemd-resolved

Please also update the website: https://one.one.one.one

Source:
https://man.archlinux.org/man/resolved.conf.5#OPTIONS

* Spell out that one.one.one.one addition is for DoT

* Add specific DNSOverTLS option

---------

Co-authored-by: Rebecca Tamachiro <[email protected]>

Author: makuru-org

src/content/docs/1.1.1.1/setup/linux.mdx

@@ -53,6 +53,13 @@ sudo <EDITOR> /etc/systemd/resolved.conf
 [Resolve]
 DNS=1.1.1.1
 ```
+To use DNS over TLS, add `#one.one.one.one` and set `DNSOverTLS` to `yes`, as in the following example:
+
+```txt
+[Resolve]
+DNS=1.1.1.1#one.one.one.one
+DNSOverTLS=yes
+```
 
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