[DNS] Update cname-domain-verification troubleshooting (cloudflare#23639)

* Update cname-domain-verification.mdx

Updating DNS Troubleshooting for CNAME records to reflect the change in name of the CNAME flattening setting and the addition of per record flattening.

* Update #causes with most recent scenarios as well

* Style guide adjustments and consolidate bullets under #solution

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

Author: 2 people

src/content/docs/dns/manage-dns-records/troubleshooting/cname-domain-verification.mdx

@@ -9,21 +9,22 @@ head:
 
 ---
 
-When configuring services from external providers - such as email services, for example - it is possible that they require you to verify your domain by placing a `CNAME` record at your zone.
+When configuring services from external providers - such as email services, for example - it is possible that they require you to verify your domain by placing a CNAME record at your zone.
 
 Consider the following sections if this is not working correctly for you.
 
 ## Causes
 
 You may find issues if you have one of the following:
 
-* The `CNAME` record you created for domain verification is set to [**Proxied**](/dns/proxy-status/).
-* The `CNAME` record is correctly set to DNS only (not proxied), but your zone has [**Flatten all CNAMEs**](/dns/cname-flattening/set-up-cname-flattening/#for-all-cname-records) option enabled.
+* The CNAME record you created for domain verification is set to [**Proxied**](/dns/proxy-status/).
+* The CNAME record is correctly set to DNS only (not proxied) but, in your [zone settings](https://dash.cloudflare.com/?to=/:account/:zone/dns/settings), [**CNAME flattening for all CNAME records**](/dns/cname-flattening/set-up-cname-flattening/#for-all-cname-records) is enabled.
+* The CNAME record is correctly set to DNS only (not proxied) but CNAME flattening is [enabled for that record specifically](/dns/cname-flattening/set-up-cname-flattening/#per-record).
 
 ## Solution
 
 Make sure that:
 
-* You have filled in the `CNAME` record fields correctly.
-* The proxy status is set to **DNS only**.
-* Under **DNS** > **Settings**, [CNAME Flattening](/dns/cname-flattening/) is set to **Flatten CNAME at apex**.
+* In your zone DNS settings: [**CNAME flattening for all CNAME records**](/dns/cname-flattening/) is disabled.
+* On the DNS records table: you have filled in the CNAME record fields correctly, proxy status is set to **DNS only**, and **Flatten** is disabled.
+