Update CODEOWNERS (#1794)

Co-authored-by: LocalStack Bot <[email protected]>

Author: localstack-bot

CODEOWNERS

@@ -39,7 +39,7 @@
 /content/en/user-guide/aws/appsync/ @cloutierMat @simonrw
 
 # athena
-/content/en/user-guide/aws/athena/ @alexrashed
+/content/en/user-guide/aws/athena/ @alexrashed @macnev2013
 
 # autoscaling
 /content/en/user-guide/aws/autoscaling/ @viren-nadkarni
@@ -104,6 +104,9 @@
 # elb
 /content/en/user-guide/aws/elb/ @simonrw
 
+# emr
+/content/en/user-guide/aws/emr/ @macnev2013
+
 # es
 /content/en/user-guide/aws/es/ @alexrashed @silv-io