Bugfix: copyright_checker should reference //:docs_sources

[ryan-steel]

Description

The copyright_checker target currently references the "docs" directory directly, but should reference //:docs_sources filegroup instead for consistency with other S-CORE repos and to ensure all documentation files are scanned. Right now the copyright_checker doesn't actually check our documentation source files, but rather the bazel build directory files.

Current Behavior

copyright_checker(
    name = "copyright",
    srcs = [
        ".github",
        "docs",  # Direct directory reference
        "examples",
        "score",
        "tools",
        "//:BUILD",
        "//:MODULE.bazel",
    ],
)

Expected Behavior

Should reference the docs_sources filegroup created by the docs() macro:

copyright_checker(
    name = "copyright",
    srcs = [
        ".github",
        "//:docs_sources",  # Use filegroup
        "examples",
        "score",
        "tools",
        "//:BUILD",
        "//:MODULE.bazel",
    ],
)