Update NU5127 docs (#3425)

Author: zivkan

docs/reference/errors-and-warnings/NU5127.md

@@ -2,9 +2,8 @@
 title: NuGet Warning NU5127
 description: NU5127 Warning code
 author: zivkan
-ms.date: 09/20/2019
+ms.date: 05/05/2025
 ms.topic: reference
-ms.reviewer: karann
 f1_keywords: 
   - NU5127
 ---
@@ -17,8 +16,17 @@ f1_keywords:
 
 ### Issue
 
-Projects using packages with `PackageReference` only use `lib/` and `ref/` assemblies to determine package compatibility. Therefore, a package without any `lib/` or `ref/` files will be considered compatible with all projects. However, if that package contains build files specific to one or more [Target Framework Monikers (TFMs)](../target-frameworks.md), a package consumer may expect the package to fail if none of the build files are used.
+Projects using packages with `PackageReference` only use `lib/` and `ref/` assemblies to determine package compatibility.
+Therefore, a package without any `lib/` or `ref/` files will be considered compatible with all projects.
+However, packages containing MSBuild props or targets that are specific to one or more target frameworks show intent in only being compatible with those target frameworks.
+
+For example, consider a package `PackageA` contains a single file, `build/net8.0/PackageA.targets`.
+If this package is referenced by a project targeting `net48` (.NET Framework, Version 4.8), NuGet will not emit any warnings or errors, but also will not select any assets from the package.
+Therefore, the package consumer will not be notified that the package does not work correctly with their project.
 
 ### Solution
 
-As the warning message suggests, create an empty file named `_._` in the lib folder for the TFMs listed. This will allow NuGet to fail the restore for `PackageReference` projects when the project is incompatible with the package.
+As the warning message suggests, create an empty file named `_._` in the lib folder for the TFMs listed.
+This will allow NuGet to fail the restore for `PackageReference` projects when the project is incompatible with the package.
+
+If your package is intended to be compatible with all target frameworks, but only take effect for certain target frameworks, create a file `build/{PackageId}.props` whose contents are `<Project />`.