docs: add comments for all functions

util/common/multi_error.go

@@ -4,8 +4,10 @@ import (
 	"strings"
 )
 
+// multiError represents a collection of errors.
 type multiError []error
 
+// Error returns a string representation of all errors joined with " | ".
 func (e multiError) Error() string {
 	var r strings.Builder
 	r.WriteString("multierr: ")
@@ -16,6 +18,7 @@ func (e multiError) Error() string {
 	return r.String()
 }
 
+// Combine combines multiple errors into a single error, filtering out nil errors.
 func Combine(maybeError ...error) error {
 	var errs multiError
 	for _, err := range maybeError {