[chore] Promote Christos Markou to Approver (#36244)

#### Description

Promote @ChrsMark to Approver. Christos has been an essential community
member for our kubernetes components and more whose judgement is well
valued.

- PRs reviewed:
https://github.com/open-telemetry/opentelemetry-collector-contrib/pulls?q=is%3Apr+reviewed-by%3AChrsMark+
- PRs authored:
https://github.com/open-telemetry/opentelemetry-collector-contrib/pulls?q=is%3Apr+author%3AChrsMark+
- Issues created:
https://github.com/open-telemetry/opentelemetry-collector-contrib/issues?q=is%3Aissue+author%3AChrsMark+
- Issues commented:
https://github.com/open-telemetry/opentelemetry-collector-contrib/issues?q=is%3Aissue+commenter%3AChrsMark+
- Commits:
https://github.com/open-telemetry/opentelemetry-collector-contrib/commits?author=ChrsMark&since=2023-05-31&until=now

.github/auto_assign.yml

@@ -12,6 +12,7 @@ assigneeGroups:
   approvers_maintainers:
     # Approvers
     - atoulme
+    - ChrsMark
     # - crobert-1 on leave
     - dashpole
     - mwear

README.md

@@ -70,7 +70,6 @@ See [CONTRIBUTING.md](CONTRIBUTING.md).
 Triagers ([@open-telemetry/collector-contrib-triagers](https://github.com/orgs/open-telemetry/teams/collector-contrib-triagers))
 
 - [Benedikt Bongartz](https://github.com/frzifus), Red Hat
-- [Christos Markou](https://github.com/ChrsMark), Elastic
 - [Jared Tan](https://github.com/JaredTan95), DaoCloud
 - [Murphy Chen](https://github.com/Frapschen), DaoCloud
 - [Paulo Janotti](https://github.com/pjanotti), Splunk
@@ -87,6 +86,7 @@ Emeritus Triagers:
 Approvers ([@open-telemetry/collector-contrib-approvers](https://github.com/orgs/open-telemetry/teams/collector-contrib-approvers)):
 
 - [Antoine Toulme](https://github.com/atoulme), Splunk
+- [Christos Markou](https://github.com/ChrsMark), Elastic
 - [Curtis Robert](https://github.com/crobert-1), Splunk (on leave)
 - [David Ashpole](https://github.com/dashpole), Google
 - [Matt Wear](https://github.com/mwear), Lightstep