[DNS] Add settings on dash to Foundation DNS features (#18833)

* Update Foundation DNS docs to refer more settings in Dash

* Create and apply partial about Foundation DNS and Dash

* Revert "Create and apply partial about Foundation DNS and Dash"

This reverts commit b2529b2.

* Process PM feedback

Author: RebeccaTamachiro

src/content/docs/dns/foundation-dns/index.mdx

@@ -14,7 +14,11 @@ With Foundation DNS, you get access to increased reliability, security, and insi
   * Strategically distributed IPs to enhance resiliency
   * Reduced exposure to incidents or software regression
   * More consistent nameserver assignment
-* DNSSEC keys unique to your account
+* DNSSEC keys unique to your zone
+* Additional DNS settings, including:
+  * [Zone defaults](/dns/additional-options/dns-zone-defaults/)
+  * [Account custom nameservers](/dns/nameservers/custom-nameservers/account-custom-nameservers/)
+  * Custom [SOA record](/dns/manage-dns-records/reference/dns-record-types/#soa) and [Nameserver TTL](/dns/nameservers/nameserver-options/#nameserver-ttl)
 
 ## Availability