Specify what Auto means for unproxied records TTL

Author: RebeccaTamachiro

src/content/docs/dns/manage-dns-records/reference/ttl.mdx

@@ -28,6 +28,8 @@ It may take longer than 5 minutes for you to actually experience record changes,
 
 For **DNS only** records, you can choose a TTL between **30 seconds** (Enterprise) or **60 seconds** (non-Enterprise) and **1 day**.
 
+A TTL of **Auto** is set to 300 seconds (5 minutes).
+
 ## Nameserver TTL
 
 [Nameserver TTL](/dns/nameservers/nameserver-options/#nameserver-ttl) is a separate feature and only affects Cloudflare nameservers and custom nameservers. For other [NS records](/dns/manage-dns-records/reference/dns-record-types/#ns) on your DNS records table, TTL is controlled by their respective TTL fields.