fix: Add more examples of correctly placed DNS TXT record for SSO setup (#25587)

## Context / Background
Dashboard SSO setup recently got way easier. The DNS TXT record strategy
for quickly verifying that someone has administrative control over a
particular domain name works great.

But, there has been a small bit of confusion about how to correctly
configure the DNS TXT record, so this change is just adding a section
that will help users check their own work and ensure the TXT record was
correctly placed.

 ## In this PR
- Updated `dash-sso-apps.mdx` to add a guide to run a test and see if
the DNS record was correctly placed.

Author: nkcmr

src/content/docs/cloudflare-one/applications/configure-apps/dash-sso-apps.mdx

@@ -68,9 +68,18 @@ curl "https://api.cloudflare.com/client/v4/accounts/{account_id}/sso_connectors"
 
 ## 3. Verify domain ownership
 
-Copy the verification code (for example `cloudflare_dashboard_sso=1111111`) and create a TXT record in your DNS configuration with that value. Cloudflare will automatically poll that DNS record until it is found or a timeout is reached within two days.
+Copy the verification code (for example `cloudflare_dashboard_sso=1111111`) and create a `TXT` record in your DNS configuration with that value. To test that the DNS record was correctly configured, you can use the `dig` command to query your email domain:
 
-If verification fails due to timeout, you may manually reinitiate the polling by running the following command:
+```sh
+dig cool.cats TXT +short
+```
+```sh output
+"cloudflare_dashboard_sso=111111111"
+```
+
+The `TXT` record must include the `cloudflared_dashboard_sso=` prefix along with the numerical code.
+
+Cloudflare will automatically poll this DNS record until it is found or a timeout is reached within two days. If verification fails due to timeout, you may manually reinitiate the polling by running the following command:
 
 ```bash title="cURL command"
 curl "https://api.cloudflare.com/client/v4/accounts/{account_id}/sso_connectors/{sso_connector_id}/begin_verification" \