Add a lot of documentation

sasl_initial_response.go

@@ -14,8 +14,11 @@ type SASLInitialResponse struct {
 	Data          []byte
 }
 
+// Frontend identifies this message as sendable by a PostgreSQL frontend.
 func (*SASLInitialResponse) Frontend() {}
 
+// 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 *SASLInitialResponse) Decode(src []byte) error {
 	*dst = SASLInitialResponse{}
 
@@ -35,6 +38,7 @@ func (dst *SASLInitialResponse) 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 *SASLInitialResponse) Encode(dst []byte) []byte {
 	dst = append(dst, 'p')
 	sp := len(dst)
@@ -51,6 +55,7 @@ func (src *SASLInitialResponse) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *SASLInitialResponse) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type          string