Remove unnecessary sentence

Author: tigrannajaryan

specification/protocol/otlp.md

@@ -423,8 +423,6 @@ for mapping between Protobuf and JSON, with the following deviations from that m
   message as if the unknown field was not resent in the payload.
   This aligns with the behavior of the Binary Protobuf unmarshaler and ensures that adding
   new fields to OTLP messages does not break existing receivers.
-  Protobuf unmarshalling implementations often support this via an option called
-  "Ignore unknown fields".
 
 Note that according to [Protobuf specs](
 https://developers.google.com/protocol-buffers/docs/proto3#json) 64-bit integer