Add documentation for the new "Spacer" paragraph

[trubach]

Documentation for the new "Spacer" paragraph needs to be added to https://drupal.webtheme.illinois.edu/

At least two new pages will need to be added to the site:

• A page under the "Paragraphs" main navigation item
  • The page should demonstrate how the spacer paragraph functions and the difference between the small, medium, and large options
• A tutorial page under Tutorials -> Adding paragraphs
  • This page should include screenshots of the editing interface using Paragraphs and instructions on how to use the paragraph. See https://drupal.webtheme.illinois.edu/tutorials/adding-paragraphs/big-buttons as an example

[github-actions]

Branch hpleas/issue-1333-add-documentation-for-the-new-spacer-paragraph created!

[trubach]

New pages at:

https://drupal.webtheme.illinois.edu/tutorials/adding-paragraphs/spacer

https://drupal.webtheme.illinois.edu/paragraphs/spacer