preview-builds: Add preview-url-path input

This way we can set `/reference` for reference repos

Author: reakaleek

.github/workflows/preview-build.yml

@@ -30,6 +30,11 @@ on:
         type: string
         default: 'false'
         required: false
+      preview-url-path:
+        description: 'Path to the preview URL'
+        type: string
+        required: false
+        default: ''
 
 permissions:
   id-token: write
@@ -169,13 +174,14 @@ jobs:
         if: always() && steps.deployment.outputs.result
         env:
           PR_NUMBER: ${{ github.event.pull_request.number }}
+          PREVIEW_URL_PATH: ${{ inputs.preview-url-path }}
         with:
           script: |
             await github.rest.repos.createDeploymentStatus({
               owner: context.repo.owner,
               repo: context.repo.repo,
               deployment_id: ${{ steps.deployment.outputs.result }},
               state: "${{ steps.docs-build.outputs.skip == 'true' && 'inactive' || (steps.s3-upload.outcome == 'success' && 'success' || 'failure') }}",
-              environment_url: `https://docs-v3-preview.elastic.dev${process.env.PATH_PREFIX}`,
+              environment_url: `https://docs-v3-preview.elastic.dev${process.env.PATH_PREFIX}${PREVIEW_URL_PATH}`,
               log_url: `https://github.com/${context.repo.owner}/${context.repo.repo}/actions/runs/${context.runId}`,
             })