Update and rename doc-preview.yml to docs-preview.yml (#3601) (#3775)

(cherry picked from commit f3daba8)

Co-authored-by: Brandon Morelli <[email protected]>

.github/workflows/docs-preview.yml

@@ -0,0 +1,23 @@
+name: docs-preview
+on:
+  pull_request_target:
+    types: [opened]
+    paths:
+      - '**.asciidoc'
+      - '**.jpg'
+      - '**.png'
+      - '**.gif'
+
+permissions:
+  pull-requests: write
+
+jobs:
+  doc-preview-pr:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: elastic/docs/.github/actions/docs-preview@master
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          repo: ${{ github.event.repository.name }}
+          preview-path: 'guide/index.html'
+          pr: ${{ github.event.pull_request.number }}