Forum page (or for digital garden)

[rufuspollock]

Create a landing page for our forum that explains briefly what it is and how to participate (github may be a bit off-putting for some people etc etc).

Acceptance

• [ ] /forum/ page exists
• [ ] brief intro to what forum is
• [ ] brief intro to how it works (maybe walking through with images how to sign up and participate especially starting with introducing yourself!)
• [ ] (bonus): list some top "forum posts"

[rufuspollock]

Think this should convert to being the digital garden section ...