Add more code owners to core (#6482)

.github/CODEOWNERS

@@ -9,14 +9,14 @@
 /sdk/ @ramya-rao-a
 
 # Core
-/sdk/core/abort-controller/ @chradek
+/sdk/core/abort-controller/ @chradek @xirzec @bterlson
 /sdk/core/core-amqp/ @ramya-rao-a @chradek
-/sdk/core/core-auth/ @daviwil
-/sdk/core/core-http/ @daviwil
-/sdk/core/core-lro/ @sadasant
-/sdk/core/core-paging/ @daviwil
-/sdk/core/core-tracing/ @xirzec
-/sdk/core/logger @xirzec
+/sdk/core/core-auth/ @daviwil @xirzec @bterlson
+/sdk/core/core-http/ @daviwil @xirzec @bterlson
+/sdk/core/core-lro/ @sadasant @xirzec @bterlson
+/sdk/core/core-paging/ @daviwil @xirzec @bterlson
+/sdk/core/core-tracing/ @xirzec @bterlson
+/sdk/core/logger @xirzec @bterlson
 
 # Service teams
 /sdk/appconfiguration/ @richardpark-msft