Joshfischer/fix rat excludes

[joshfischer1108]

Before this PR we would get output from Apache Rat saying we had a .bzl file without a header. This file is not included in the release and does not need one. I also added explicit listings for the website2 and generate-site folders as they were showing up in the Rat report.

 Printing headers for text files without a valid license header...
 
=====================================================
== File: ./tools/travis/toolchain/cc_toolchain_config.bzl
=====================================================
def _impl(ctx):
    return cc_common.create_cc_toolchain_config_info(
        ctx = ctx,
        toolchain_identifier = "k8-toolchain",
        host_system_name = "local",
        target_system_name = "local",
        target_cpu = "k8",
        target_libc = "unknown",
        compiler = "clang",
        abi_version = "unknown",
        abi_libc_version = "unknown",
    )

cc_toolchain_config = rule(
    implementation = _impl,
    attrs = {},
    provides = [CcToolchainConfigInfo],
)

To reproduce my findings execute the following on master HEAD from the root folder of the project.

sh ./scripts/release_check/license_check.sh ~/Desktop/apache-rat-0.13/apache-rat-0.13.jar