docs: add documentation comments to validation helper methods

Add proper godoc comments to Tag validation methods:
- Valid(): Documents tag content validation strategy
- validateComidTag(): Describes CoMID tag validation
- validateCoswidTag(): Describes CoSWID tag validation
- validateGenericCBOR(): Describes generic CBOR validation

These comments improve code documentation and help future maintainers
understand the validation flow for different tag types.

Signed-off-by: 7908837174 <[email protected]>
Signed-off-by: Kallal Mukherjee <[email protected]>

Author: kallal79

corim/unsignedcorim.go

@@ -342,6 +342,10 @@ type Tag struct {
 	Content []byte
 }
 
+// Valid validates the tag content based on its tag number.
+// For CoMID tags (506), it unmarshals and validates the content.
+// For CoSWID tags (505), it validates the CoSWID structure.
+// For other tags, it ensures the content is valid CBOR.
 func (o Tag) Valid() error {
 	if len(o.Content) == 0 {
 		return errors.New("empty tag")
@@ -357,6 +361,7 @@ func (o Tag) Valid() error {
 	}
 }
 
+// validateComidTag unmarshals and validates CoMID tag content.
 func (o Tag) validateComidTag() error {
 	var c comid.Comid
 	if err := dm.Unmarshal(o.Content, &c); err != nil {
@@ -370,6 +375,7 @@ func (o Tag) validateComidTag() error {
 	return nil
 }
 
+// validateCoswidTag validates CoSWID tag content by attempting to unmarshal it.
 func (o Tag) validateCoswidTag() error {
 	var s swid.SoftwareIdentity
 	if err := dm.Unmarshal(o.Content, &s); err != nil {
@@ -379,6 +385,7 @@ func (o Tag) validateCoswidTag() error {
 	return nil
 }
 
+// validateGenericCBOR ensures the tag content is valid CBOR for unknown tag types.
 func (o Tag) validateGenericCBOR() error {
 	var raw interface{}
 	if err := dm.Unmarshal(o.Content, &raw); err != nil {