Add a lot of documentation

parameter_status.go

@@ -12,8 +12,11 @@ type ParameterStatus struct {
 	Value string
 }
 
+// Backend identifies this message as sendable by the PostgreSQL backend.
 func (*ParameterStatus) 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 *ParameterStatus) Decode(src []byte) error {
 	buf := bytes.NewBuffer(src)
 
@@ -33,6 +36,7 @@ func (dst *ParameterStatus) 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 *ParameterStatus) Encode(dst []byte) []byte {
 	dst = append(dst, 'S')
 	sp := len(dst)
@@ -48,6 +52,7 @@ func (src *ParameterStatus) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (ps *ParameterStatus) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type  string