Sync eng/common directory with azure-sdk-tools for PR 1615 (Azure#15346)

* Move docindex.yml from steps -> jobs

* Add docindex.yml

Co-authored-by: Daniel Jurek <djurek@microsoft.com>

Author: azure-sdk

…n/pipelines/templates/steps/docindex.yml …on/pipelines/templates/jobs/docindex.ymleng/common/pipelines/templates/steps/docindex.yml renamed to eng/common/pipelines/templates/jobs/docindex.yml eng/common/pipelines/templates/steps/docindex.yml renamed to eng/common/pipelines/templates/jobs/docindex.yml

@@ -0,0 +1,4 @@
+trigger: none
+
+jobs:
+  - template: /eng/common/pipelines/templates/jobs/docindex.yml