[Minor-Fix][626] Add description for Color vocabulary.

[ivan-berezhnov]

Make sure these boxes are checked before asking for review of your pull request - thank you!

General checks

• All coding styles are fulfilled and there are no any issues reported by CodeSniffer CI.
  
• All tests are running and there are no failed tests reported by CI.
  
• Documentation has been updated according to PR changes.
• Steps for review have been provided according to PR changes.
  
• Make sure you've provided all necessary hook_update_N to support upgrade path.
• Make sure your git email is associated with account on drupal.org, otherwise you won't get commits there.
  
• If you would like to get credits on drupal.org, check documentation.

Thank you for your contribution!

Issue:

#626
Drupal.org issue: https://www.drupal.org/node/2889897

Steps to review:

• login as admin
• go to [sitename]/admin/structure/taxonomy
• verify Color vocabulary have description and text as in issue.

[gundevel]

Build comment file:

===============

Environment	Link
Fresh OpenY installation	http://ci.openymca.org/build1745
Upgraded(upgrade path) installation	http://upgrade.openy-dev.ffwua.com/build1745
Installation process	http://install.openy-dev.ffwua.com/build1745/install.php

---

Test PASSed.
Refer to this link for build results (access rights to CI server needed):
http://ci.openymca.org:8080/job/PR_BUILDER/1745/

[gundevel]

Accessibility report http://ci.openymca.org/build1745

[gundevel]

Decoupling report http://ci.openymca.org/build1745