Note that only one 'override' for a given package name is acceptable. (…

…#438)

Resolves microsoft/vcpkg-tool#1573 (comment)

vcpkg/users/versioning.md

@@ -4,7 +4,7 @@ title: Versioning reference
 description: Reference documentation for the vcpkg versioning feature.
 author: vicroms
 ms.author: viromer
-ms.date: 3/1/2024
+ms.date: 1/16/2025
 ms.topic: reference
 ---
 # Versioning reference
@@ -162,6 +162,8 @@ Overrides are declared as an array of package version declarations.
 
 For an override to take effect, the overridden package must form part of the dependency graph. That means that a dependency must be declared either by the top-level manifest or be part of a transitive dependency.
 
+Only one override may be declared for a given name.
+
 ```json
 {
   "name": "project",