Updates to suggestions process and CSS refresh

[KellyStathis]

Purpose

Update the "Contribute" page and other places to reflect new suggestions process.

Approach

• text updates to "Contribute" page and "Feedback" section of homepage
• miscellaneous CSS changes to align more with Commons and Fabrica look and feel

Open Questions and Pre-Merge TODOs

Learning

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)

• [x] New feature (non-breaking change which adds functionality)

• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Reviewer, please remember our guidelines:

• Be humble in the language and feedback you give, ask don't tell.
• Consider using positive language as opposed to neutral when offering feedback. This is to avoid the negative bias that can occur with neutral language appearing negative.
• Offer suggestions on how to improve code e.g. simplification or expanding clarity.
• Ensure you give reasons for the changes you are proposing.