Update navigation.mdx

changed topbarCTA -> topbarCtaButton

Author: dino475

settings/navigation.mdx

@@ -215,10 +215,10 @@ field.
   <img className="block rounded-md" src="/images/topbar-cta-get-started.png" />
 </Frame>
 
-The `topbarCTA` field supports the following fields: `name`, `url`, and `type`.
+The `topbarCtaButton` field supports the following fields: `name`, `url`, and `type`.
 
 ```json
-  "topbarCTA": {
+  "topbarCtaButton": {
     "name": "Get Started",
     "url": "https://mintlify.com/get-started"
   }