Fix typo in URL.

cmake/DirectX-Headers.pc.in

@@ -4,7 +4,7 @@ includedir=@DIRECTX_INCLUDEDIR_FOR_PKG_CONFIG@
 
 Name: @PROJECT_NAME@
 Description: Headers for using D3D12
-URL: https://github.com/microsoft/DirectX-Header
+URL: https://github.com/microsoft/DirectX-Headers
 Version: @PROJECT_VERSION@
 Cflags: -I${includedir}
 Libs: -lDirectX-Headers -lDirectX-Guids