Adds Josh Romero as co-maintainer (opensearch-project#1682)

I nominate Josh Romero (@joshuarrrr) as co-maintainer and the 
OpenSearch Dashboards maintainers unanimously approve this 
nomination.

Josh has consistently contributed high-quality PRs and is actively
improving both the developer and user experience through contributions
such as migrating all mocha tests to jest and working with the community
to redesign the OpenSearch Dashboards global header.

https://github.com/opensearch-project/OpenSearch-Dashboards/pulls/joshuarrrr

Josh privately accepted this nomination.

Thank you for your contributions Josh!

Signed-off-by: Tommy Markley <markleyt@amazon.com>

MAINTAINERS.md

@@ -11,5 +11,6 @@
 | Tommy Markley | [tmarkley](https://github.com/tmarkley) | Amazon | 
 | Miki Barahmand | [AMoo-Miki](https://github.com/AMoo-Miki) | Amazon |
 | Ashwin P Chandran | [ashwin-pc](https://github.com/ashwin-pc) | Amazon |
+| Josh Romero | [joshuarrrr](https://github.com/joshuarrrr) | Amazon |
 
 [This document](https://github.com/opensearch-project/.github/blob/main/MAINTAINERS.md) explains what maintainers do, and how they should be doing it. If you're interested in contributing, see [CONTRIBUTING](CONTRIBUTING.md).