[CI] Update labels for doc issue creation workflow (#1789)

Example:
https://github.com/opensearch-project/OpenSearch-Dashboards/runs/7015324767?check_suite_focus=true

If we checkout the run, we can see the run fails with:
`Resource not accessible by integration`

Which I believe because the `documentation` label is not available in the doc repo. So instead of
creating a `documentation` label which seems redudant for a doc repo issue, we should use
`dashboards` because it exists and makes it more specific for the doc repo maintainers.

Issue:
n/a

Signed-off-by: Kawika Avilla <[email protected]>

.github/workflows/create_doc_issue.yml

@@ -34,7 +34,7 @@ jobs:
         with:
           title: Add documentation related to new feature
           content-filepath: ./.github/doc_issue_template.md
-          labels: documentation
+          labels: dashboards
           repository: opensearch-project/documentation-website
           token: ${{ steps.github_app_token.outputs.token }}