[DIS2-1072] Update linkPlain documentation.

[amir-clever]

Jira: https://clever.atlassian.net/browse/DIS2-1072

Overview: Improve documentation for linkPlain.

Screenshots/GIFs:

Testing:

• [n/a] Unit tests
• Manual tests:
  • [x] Chrome
  • [ ] Safari
  • [ ] IE10

Roll Out:

• Before merging:
  • [x] Updated docs
  • [n/a] Bumped version in package.json
    • Breaking change? Run npm version minor
    • Backward compatible change? Run npm version patch
    • Only changing documentation? All good. Skip this step.
• After merging:
  • [ ] Deployed updated docs (make deploy-docs)