THRIFT-5541: Clarify on THeader key/value format in the spec
THRIFT-5541: Clarify on THeader key/value format in the spec

[skip ci]

apache/thrift,apache/thrift,apache/thrift,apache/thrift,Jens-G/thrift,jeking3/thrift,Jens-G/thrift,jeking3/thrift,jeking3/thrift,Jens-G/thrift,Jens-G/thrift,apache/thrift,Jens-G/thrift,jeking3/thrift,apache/thrift,apache/thrift,jeking3/thrift,nsuke/thrift,nsuke/thrift,Jens-G/thrift,jeking3/thrift,nsuke/thrift,apache/thrift,apache/thrift,Jens-G/thrift,jeking3/thrift,Jens-G/thrift,nsuke/thrift,nsuke/thrift,nsuke/thrift,nsuke/thrift,jeking3/thrift,jeking3/thrift,jeking3/thrift,nsuke/thrift,nsuke/thrift,Jens-G/thrift,jeking3/thrift,apache/thrift,nsuke/thrift,apache/thrift,nsuke/thrift,apache/thrift,nsuke/thrift,Jens-G/thrift,jeking3/thrift,apache/thrift,jeking3/thrift,Jens-G/thrift,nsuke/thrift,Jens-G/thrift,apache/thrift,jeking3/thrift,nsuke/thrift,nsuke/thrift,Jens-G/thrift,Jens-G/thrift,nsuke/thrift,jeking3/thrift,jeking3/thrift,apache/thrift,apache/thrift,Jens-G/thrift,nsuke/thrift,Jens-G/thrift,Jens-G/thrift,apache/thrift,Jens-G/thrift,apache/thrift