docs: remove a TODO that shows up in the docs (#30440)

Signed-off-by: Peter Jausovec <peter.jausovec@solo.io>

Mirrored from https://github.com/envoyproxy/envoy @ 7a44ebbd2b5a00f846a09b48d578d28355221115

envoy/extensions/filters/http/json_to_metadata/v3/json_to_metadata.proto

@@ -62,7 +62,6 @@ message JsonToMetadata {
   }
 
   message Selector {
-    // TODO(kuochunghsu): Explore matchers for array handling.
     oneof selector {
       // key to match
       string key = 1 [(validate.rules).string = {min_len: 1}];