Add Newsletters Docs To Dev Server (#14094)

Adds documentation for the all newsletters page, which can be rendered
on dotcom only.

Author: JamieB-gu

dotcom-rendering/src/devServer/docs/newsletters.tsx

@@ -0,0 +1,18 @@
+import { Available } from './available';
+
+export const Newsletters = () => (
+	<>
+		<Available targets={['dotcom']} />
+		<p>
+			The{' '}
+			<a href="https://www.theguardian.com/email-newsletters">
+				all newsletters page
+			</a>{' '}
+			is a list of the currently published Editorial email newsletters,
+			and includes a way to sign up to several at once. It's powered by
+			the Newsletters API and configured in the Newsletters Tool. The
+			email newsletters themselves are rendered by{' '}
+			<code>email-rendering</code> and <code>frontend</code>, not DCAR.
+		</p>
+	</>
+);

dotcom-rendering/src/devServer/routers/dotcom.ts

@@ -3,6 +3,7 @@ import { Article } from '../docs/article';
 import { Dotcom } from '../docs/dotcom';
 import { Front } from '../docs/front';
 import { Interactive } from '../docs/interactive';
+import { Newsletters } from '../docs/newsletters';
 import { TagPage } from '../docs/tagPage';
 import { sendReact } from '../send';
 
@@ -13,5 +14,6 @@ dotcom.get('/article', sendReact('Article', Article));
 dotcom.get('/front', sendReact('Front', Front));
 dotcom.get('/tag-page', sendReact('Tag Page', TagPage));
 dotcom.get('/interactive', sendReact('Interactive', Interactive));
+dotcom.get('/newsletters', sendReact('All Newsletters', Newsletters));
 
 export { dotcom };

dotcom-rendering/src/devServer/routers/pages.ts

@@ -2,6 +2,7 @@ import { Router } from 'express';
 import { Article } from '../docs/article';
 import { Front } from '../docs/front';
 import { Interactive } from '../docs/interactive';
+import { Newsletters } from '../docs/newsletters';
 import { Pages } from '../docs/pages';
 import { TagPage } from '../docs/tagPage';
 import { sendReact } from '../send';
@@ -13,5 +14,6 @@ pages.get('/article', sendReact('Article', Article));
 pages.get('/front', sendReact('Front', Front));
 pages.get('/tag-page', sendReact('Tag Page', TagPage));
 pages.get('/interactive', sendReact('Interactive', Interactive));
+pages.get('/newsletters', sendReact('All Newsletters', Newsletters));
 
 export { pages };