[SSL] Call out cert is only forwarded on first request (#18572)

* Update forward-client-certificate.mdx

added note about cert only being forwarded on first request

* Replace cert by full form and separate from plan callout

---------

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

Author: chris-martinelli

src/content/partials/ssl/forward-client-certificate.mdx

@@ -7,9 +7,10 @@
 
 In addition to enforcing mTLS authentication for your host, you can also forward a client certificate to your origin server as an HTTP header. This setup is often helpful for server logging.
 
-:::caution
+To avoid adding the certificate to every single request, the certificate is only forwarded on the first request of an mTLS connection.
 
-This process is only available on accounts with [Cloudflare Access](/cloudflare-one/). 
+:::caution
+This process is only available on accounts with [Cloudflare Access](/cloudflare-one/).
 :::
 
 ### Cloudflare API