Add a lot of documentation

ready_for_query.go

@@ -8,8 +8,11 @@ type ReadyForQuery struct {
 	TxStatus byte
 }
 
+// Backend identifies this message as sendable by the PostgreSQL backend.
 func (*ReadyForQuery) Backend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *ReadyForQuery) Decode(src []byte) error {
 	if len(src) != 1 {
 		return &invalidMessageLenErr{messageType: "ReadyForQuery", expectedLen: 1, actualLen: len(src)}
@@ -20,10 +23,12 @@ func (dst *ReadyForQuery) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *ReadyForQuery) Encode(dst []byte) []byte {
 	return append(dst, 'Z', 0, 0, 0, 5, src.TxStatus)
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *ReadyForQuery) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type     string