Update directory structure for documentation design models.
    
    - Previously, design models related to documentation were stored in
      the tcar-models-docs directory. This organization makes the
      repository nonfunctional in its pristine state. This update moves
      design models related to documentation from tcar-models-docs
      directory to Models/Documentation directory in order to make the
      repository functional in its pristine state.
    
    - The COPYING file was also removed to avoid duplicate copies of it.
      The place of this file is the inside the master branch.