Writing cohort banner

[corwintines]

Description

• Adds a DismissableBanner to promote the ethereum.org writing cohort

[gatsby-cloud]

✅ ethereum-org-website-dev deploy preview ready

• Deploy preview
• Build logs · 20m build time

[pettinarip]

Looks good! I left a comment for improvement.

[pettinarip]

For SSR purposes, a better way of getting the pathname is from Gatsby itself (or specifically from reach router which is what they use underneath).

// every page or template receives a `location` prop
const StaticPage = ({ data, location }) => {
  ...
}

// then you can pass that prop down to the components
<WritersCohortBanner pathname={location.pathname} />

This way you abstract yourself from the window object and you can render the same thing server and client side.

[corwintines]

Makes sense, changed this PR over to this just now.