[docs] Add the new docs CI checks (#212557)

Adds the new docs CI checks. This will enable a preview to build our new
Markdown-based docs.

@florent-leborgne please tag reviewers, add the appropriate label(s),
and take this out of draft when you're ready.

---------

Co-authored-by: florent-leborgne <florent.leborgne@elastic.co>
Co-authored-by: Brad White <Ikuni17@users.noreply.github.com>

.github/workflows/docs-build.yml

@@ -0,0 +1,22 @@
+name: docs-build
+
+on:
+  push:
+    branches:
+      - main
+  pull_request_target:
+    types:
+      - opened
+      - reopened
+      - synchronize
+
+jobs:
+  docs-preview:
+    uses: elastic/docs-builder/.github/workflows/preview-build.yml@main
+    with:
+      path-pattern: docs/**
+    permissions:
+      deployments: write
+      id-token: write
+      contents: read
+      pull-requests: read

.github/workflows/docs-cleanup.yml

@@ -0,0 +1,14 @@
+name: docs-cleanup
+
+on:
+  pull_request_target:
+    types:
+      - closed
+
+jobs:
+  docs-preview:
+    uses: elastic/docs-builder/.github/workflows/preview-cleanup.yml@main
+    permissions:
+      contents: none
+      id-token: write
+      deployments: write