[FEAT] `daff.io/docs` footer

[xelaint]

:bulb: Feature request

Feature Name

daff.io/docs` Footer

The Desired Behavior

Specific footer for daff.io/docs, different from the marketing website.

1. Include open source blurb and contributing button
2. Help section (link to discussions + contact Daffodil)

Not all docs pages have a footer right now. It needs to be visible on all pages.

Your Use Case

Prior Work

Environment

Daffodil version: X.Y.Z
Angular version: X.Y.Z 

 
For Tooling issues:
- Node version: XX  
- Platform:  

Others: