[ci] Add new docs-builder automation.

.github/workflows/docs-build.yml

@@ -0,0 +1,19 @@
+name: docs-build
+
+on:
+  push:
+    branches:
+      - main
+  pull_request_target: ~
+
+jobs:
+  preview:
+    uses: elastic/docs-builder/.github/workflows/preview-build.yml@main
+    with:
+      continue-on-error: false
+      strict: true
+    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:
+  preview:
+    uses: elastic/docs-builder/.github/workflows/preview-cleanup.yml@main
+    permissions:
+      contents: none
+      id-token: write
+      deployments: write