Missing package_type assignment in example documentation of "Package prebuilt binaries"

The example of [Package prebuilt binaries](https://docs.conan.io/2/tutorial/creating_packages/other_types_of_packages/package_prebuilt_binaries.html) does not mention the need to set an appropriate [package_type](https://docs.conan.io/2.0/reference/conanfile/attributes.html#reference-conanfile-attributes-package-type).

In case the **package_type** remains undefined, consumers using **CMakeDeps** generator will not have the a **_BIN_DIRS** variable defined in the generated finders, due to the explicit exclusion of such variable in [target_data.py:346](https://github.com/conan-io/conan/blob/release/2.0/conan/tools/cmake/cmakedeps/templates/target_data.py#L346).

As a result, users trying to use the example documentation to package a pre-existing shared library will most likely fail to run the *test_package* due to a missing DLL.