docs: add freeze columns feature

Author: mtrezza

README.md

@@ -70,6 +70,7 @@ Parse Dashboard is a standalone dashboard for managing your [Parse Server](https
       - [Audio Item](#audio-item)
       - [Button Item](#button-item)
       - [Panel Item](#panel-item)
+    - [Freeze Columns](#freeze-columns)
   - [Browse as User](#browse-as-user)
   - [Change Pointer Key](#change-pointer-key)
     - [Limitations](#limitations)
@@ -1154,6 +1155,12 @@ Example:
 }
 ```
 
+### Freeze Columns
+
+▶️ *Core > Browser > Freeze column*
+
+This feature allows freezing columns from the left up to a selected column in the data browser. When scrolling horizontally, the frozen columns remain visible while the other columns scroll underneath.
+
 ## Browse as User
 
 ▶️ *Core > Browser > Browse*