[Email Security] RBI attachment file type limitation (#23395)

* [Email Security] RBI attachment file type limitation

* Update src/content/docs/cloudflare-one/email-security/email-monitoring/search-email.mdx

Co-authored-by: Kate Tungusova <[email protected]>

---------

Co-authored-by: Kate Tungusova <[email protected]>

Author: Maddy-Cloudflare

src/content/docs/cloudflare-one/email-security/email-monitoring/search-email.mdx

@@ -236,7 +236,7 @@ Email Security displays the following details:
    - Autonomous sys name: This name identifies your autonomous system (AS).
    - Country
 4. **Links identified**: A list of malicious links identified by Email Security. Refer to [Open links](/cloudflare-one/email-security/email-monitoring/search-email/#open-links) to open links in Security Center, Browser Isolation or an external tool of your choice.
-5. **Attachments**: If an email has an attachment, the dashboard will display the filename, and the disposition assigned. You can open attachments in [Browser Isolation](/cloudflare-one/policies/browser-isolation/).
+5. **Attachments**: If an email has an attachment, the Cloudflare dashboard will display the filename, and the disposition assigned. You can open attachments in [Browser Isolation](/cloudflare-one/policies/browser-isolation/). Only PDF files are currently supported.
 6. **Reasons for disposition**: Description of why the email was deemed as malicious, suspicious, or spam.
 
 #### Open links