Fix ProjectReference path in preprocessor directives (#49507)

those two samples should refer to the same

Author: AdmiralSnyder

docs/csharp/language-reference/preprocessor-directives.md

@@ -121,7 +121,7 @@ The `#:` directives that are used in file-based apps include:
   The preceding preprocessor token is translated into:
 
   ```xml
-  <ProjectReference Include="../Path/To.Example.csproj" />
+  <ProjectReference Include="../Path/To.Example/To.Example.csproj" />
   ```
 
 Tools can add new tokens following the `#:` convention.