Remove mentioning Variables in the architecture diagram

[antalszava]

Changes the architecture diagram image such that it doesn't mention Variables.

[github-actions]

Hello. You may have forgotten to update the changelog!
Please edit .github/CHANGELOG.md with:

• A one-to-two sentence description of the change. You may include a small working example for new features.
• A link back to this PR.
• Your name (or GitHub username) in the contributors section.

[codecov]

Codecov Report

Merging #1235 (83f9937) into master (d57e5db) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1235   +/-   ##
=======================================
  Coverage   98.12%   98.12%           
=======================================
  Files         145      145           
  Lines       10981    10981           
=======================================
  Hits        10775    10775           
  Misses        206      206           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update d57e5db...83f9937. Read the comment docs.

[josh146]

Very nice PR to review @antalszava :)