[Breaking] New Custom Application docs for v21 release. (#2431)

* docs: draft migration to org-level

* chore(website): disable link checker

* refactor(website): add link to legacy docs

* docs: restructure pages, add placeholder pages

* docs(website): document more stuff

* docs: more updates

* docs: more updates

* docs: data fetching

* docs: show app icons

* docs: style adjustment

* docs: disable component pages creation, add infodialog docs

* docs: update app config

* docs: update appkit components

* docs: update appshell

* docs: more updates

* docs: cleanup

* docs: ui components

* docs: permissions

* chore: upgrade uikit to v12.2.6

* docs: cleanup

* docs: more updates

* docs: more updates

* docs: deployment examples overview

* docs: vercel

* docs: typos

* docs: improvements

* docs: typo

* docs: netlify

* docs: more deployment examples

* docs: improvements

* docs: improvements

* docs: testing

* docs: cli improvements

* docs: surge

* docs: release note breaking changes checklist

* docs: improvements

* docs: cloudflare example

* docs: improvements

* docs: typo

* docs: constants

* docs: improvements

* docs: release notes

* docs: rename icon refs

* chore: disable search index for custom domain branch

* docs: typos

* docs: adjust migration end date

* docs: adjust spacing

* chore: regenerate lockfile

* docs: improvements

* docs: more improvements

* docs: address first round of feedback

* docs: syntax improvements, adjust links

* docs: fix example domains

* docs: more typos and wording improvements

* docs: update words casing

* docs: update release note

* docs: improve examples for release note

* docs: small improvements

* refactor(docs): render global notification

* docs: improvements based on feedback

* docs: more improvements based on feedback

* docs: typo

* chore: define global notification message

* docs: improvements based on feedback

* refactor(docs): fix legacy links, rename path to legacy

* docs: improvements based on feedback

* Update support-policy.mdx

Updated the "Support Policy" page according to our agreement @emmenko. Feel free to update the name of the page as well. My current suggestion is "Support & Maintenance".

* docs: typos and improvements

* docs: update notification text

* docs: improvements based on feedback

* docs: improvements based on feedback

* refactor: run linkinator as post-deploy step

* fix(ci): linkinator config

* fix: ignore icons from link check

* docs: adjust to latest test-utils changes

* docs: remove empty pages

* docs: update release date

* docs: add code example

* docs: update release note

* docs: minor updates

* chore: remove noindex header for docs

Co-authored-by: Maxim <89984934+mmaltsev-ct@users.noreply.github.com>

.github/workflows/after-deployment.yml

@@ -0,0 +1,29 @@
+name: After deployments
+
+on: [deployment_status]
+
+jobs:
+  link-check:
+    name: 'Check links'
+
+    if: github.event.deployment_status.state == 'success'
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Setup Node (uses version in .nvmrc)
+        uses: actions/setup-node@v2
+        with:
+          node-version-file: '.nvmrc'
+
+      - name: Check links
+        uses: JustinBeckwith/linkinator-action@v1.10.0
+        with:
+          paths: ${{ github.event.deployment_status.target_url }}/custom-applications
+          config: website/linkinator.config.json
+          markdown: false
+          urlRewriteReplace: ${{ github.event.deployment_status.target_url }}
+          urlRewriteSearch: https://docs.commercetools.com

.vscode/spellright.dict

@@ -21,3 +21,5 @@ commercetools
 Intl
 IntelliSense
 Stylelint
+Cloudflare
+Flexbox

application-templates/starter/CHANGELOG.md

@@ -700,7 +700,7 @@
   - The template now has more built-in dev tools, like ESLint and Prettier.
   - The template README has been cleaned up a bit.
   - The template uses the new [React JSX transform](https://reactjs.org/blog/2020/09/22/introducing-the-new-jsx-transform.html).
-  - The template uses the new [menu links in application config](https://docs.commercetools.com/custom-applications/development/menu-links#menu-links-in-application-config).
+  - The template uses the new [menu links in application config](https://docs.commercetools.com/custom-applications/legacy/development/menu-links#menu-links-in-application-config).
   - The template has a nicer landing/welcome page with useful links to get started.
   - The template has a `channels` page, that fetches channels and renders them in a table. This is a good showcase of some of our best practices, for example to use Hooks, to use GraphQL, to use notifications, to render data in a table (with pagination), etc.
   - The template has RTL tests, including mocking GraphQL and using test data.