[BD-46] Visibility of text in an example of using the Layout component

[PKulkoRaccoonGang]

It is difficult to recognize the text in the example of using the Layout component on the Paragon documentation site.

Current state:

Proposal:

[adamstankiewicz]

@PKulkoRaccoonGang Let's just verify the foreground vs. background colors chosen here pass WCAG AA color contrast.

https://webaim.org/resources/contrastchecker/

[PKulkoRaccoonGang]

@adamstankiewicz After checking the colors for the example Layout component on the Paragon documentation site, it was discovered that all background colors (#ff0000, #008000, and #0000ff) fail accessibility checks for the #454545 text color. Those color options that were offered earlier also turned out to be invalid.

PR with valid colors (according to WCAG) #2668