TSC: Promote Mark Mercado (@mamercad) from Contributors to Maintainers (#6096)

Add mamercad to Maintainers

Author: arm4b

OWNERS.md

@@ -43,6 +43,8 @@ Being part of Technical Steering Committee (TSC) [@StackStorm/maintainers](https
   - StackStorm Core, Workflows.
 * Marcel Weinberg ([@winem](https://github.com/winem)), _CoreMedia_ <<mweinberg-os@email.de>>
   - Systems, Core, CI/CD, Docker, Community.
+* Mark Mercado ([@mamercad](https://github.com/mamercad)), _DigitalOcean_ <<mmercado@digitalocean.com>>
+  - Ansible, Docker, K8s, StackStorm Exchange. [StackStorm Adoption](https://github.com/StackStorm/st2/pull/5836)
 * Mick McGrath ([@mickmcgrath13](https://github.com/mickmcgrath13)), _Bitovi_ <<mick@bitovi.com>>
   - Systems, ST2 Exchange. [Case Study](https://stackstorm.com/case-study-bitovi/).
 
@@ -55,7 +57,6 @@ They're not part of the TSC voting process, but appreciated for their contributi
 * Anand Patel ([@arms11](https://github.com/arms11)), _VMware_ - Docker, Kubernetes.
 * Harsh Nanchahal ([@hnanchahal](https://github.com/hnanchahal)), _Starbucks_ - Core, Docker, Kubernetes.
 * Hiroyasu Ohyama ([@userlocalhost](https://github.com/userlocalhost)) - Orquesta, Workflows, st2 Japan Community. [Case Study](https://stackstorm.com/case-study-dmm/).
-* Mark Mercado ([@mamercad](https://github.com/mamercad)), _DigitalOcean_ - Ansible, Docker, K8s, StackStorm Exchange. [StackStorm Adoption](https://github.com/StackStorm/st2/pull/5836).
 * Rick Kauffman ([@xod442](https://github.com/xod442)), _HPE_ - Community, HOWTOs, Blogs, Publications, Docker.
 * Sheshagiri Rao Mallipedhi ([@sheshagiri](https://github.com/sheshagiri)) - Docker, Core, StackStorm Exchange.
 * Shital Raut ([@shital-orchestral](https://github.com/shital-orchestral)), _Orchestral.ai_ - Web UI.