docs: Fix Antora start_path for all components
    
    This commit fixes all Antora configuration files for the components
    underneath this repository. When you run the build script, it reports
    errors that it is unable to find the reference for the `start_path` for
    all of the components. This is because the full path is required,
    including the `.adoc` file ending. So, this commit makes the path
    explicit and therefore, fixes the errors.
    
    Signed-off-by: Justin W. Flory (he/him) <jwf@redhat.com>