chore: removing Oberon00 from approvers (open-telemetry#770)

Co-authored-by: Yusuke Tsutsumi <yusuke@tsutsumi.io>

README.md

@@ -105,7 +105,6 @@ Approvers ([@open-telemetry/python-approvers](https://github.com/orgs/open-telem
 
 - [Carlos Alberto Cortez](https://github.com/carlosalberto), LightStep
 - [Chris Kleinknecht](https://github.com/c24t), Google
-- [Christian Neumüller](https://github.com/Oberon00), Dynatrace
 - [Diego Hurtado](https://github.com/ocelotl)
 - [Hector Hernandez](https://github.com/hectorhdzg), Microsoft
 - [Leighton Chen](https://github.com/lzchen), Microsoft
@@ -119,6 +118,12 @@ Maintainers ([@open-telemetry/python-maintainers](https://github.com/orgs/open-t
 - [Alex Boten](https://github.com/codeboten), LightStep
 - [Yusuke Tsutsumi](https://github.com/toumorokoshi), Zillow Group
 
+### Thanks to all the people who already contributed!
+
+<a href="https://github.com/open-telemetry/opentelemetry-python/graphs/contributors">
+  <img src="https://contributors-img.web.app/image?repo=open-telemetry/opentelemetry-python" />
+</a>
+
 *Find more about the maintainer role in [community repository](https://github.com/open-telemetry/community/blob/master/community-membership.md#maintainer).*
 
 ## Release Schedule