Update CODEOWNERS to include core-platform members

Author: ErikAtSumo

.github/CODEOWNERS

@@ -2,10 +2,9 @@
 # Each line is a file pattern followed by one or more owners.
 
 # These owners will be the default owners for everything in
-# the repo. Unless a later match takes precedence,
-# @sumovishal, @dagould will be requested for
-# review when someone opens a pull request.
-*       @sumovishal @dagould
+# the repo. Unless a later match takes precedence, they will
+# be requested for review when someone opens a pull request.
+*       @sumovishal @ashpaliwal @adisuj @ErikAtSumo @sjain05
 
 # Code owners for collection sources
 /sumologic/*_source.go        @maimaisie @vsinghal13