added changelog for api playground + auth preview deployments (#458)

Co-authored-by: Hahnbee Lee <[email protected]>

Author: tiffany-mintlify

changelog/overview.mdx

@@ -9,7 +9,7 @@ mode: "center"
 ## docs.json replacing mint.json
 Upgrades include better multi-level versioning, easier visual comprehension, and more consistent terminology. 
 
-[Update your Mintlify CLI](/settings/global). 
+[Update your Mintlify CLI](/navigation/config-upgrade#upgrading-from-mint-json-to-docs-json). 
 
 ## CI Checks
 Automatically lint your docs to find broken links, discover spelling and grammar issues, or enforce writing styles with your own Vale config. Learn more in our [docs](settings/ci). 
@@ -32,7 +32,17 @@ Now available:
 - Improved mint.json file editing
 
 ## Partial Authentication
-Customize access to any page or section of content depending on user permissions. Supports connecting with your own authentication system. 
+Customize access to any page or section of content depending on user permissions. Supports connecting with your own authentication system.
+
+## Revamped API Playground
+We’ve overhauled the design and performance of the [API Playground](/api-playground/). Updates include:
+
+- Easier detail expansion for an overview of a field
+- More intuitive nested design, e.g. adding or deleting items
+- Faster response times
+
+## Quality Improvements
+- Support for requiring authentication to access preview deployments
 
 </Update>
 
@@ -43,8 +53,6 @@ Customize access to any page or section of content depending on user permissions
     </Frame> 
     Make docs private by setting up authentication via JWT, OAuth, or a universal password. With this privacy, you can create an internal knowledge base or prevent competitors from seeing your docs.
 
-
-
 </Update>