Update files based on go lint

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

errdefs/errors.go

@@ -29,6 +29,7 @@ var (
 	ErrNotImplemented     = errors.New("not implemented") // represents not supported and unimplemented
 )
 
+// IsInvalidArgument returns true if the error is due to an invalid argument
 func IsInvalidArgument(err error) bool {
 	return errors.Cause(err) == ErrInvalidArgument
 }
@@ -45,15 +46,17 @@ func IsAlreadyExists(err error) bool {
 }
 
 // IsFailedPrecondition returns true if an operation could not proceed to the
-// lack of a particular condition.
+// lack of a particular condition
 func IsFailedPrecondition(err error) bool {
 	return errors.Cause(err) == ErrFailedPrecondition
 }
 
+// IsUnavailable returns true if the error is due to a resource being unavailable
 func IsUnavailable(err error) bool {
 	return errors.Cause(err) == ErrUnavailable
 }
 
+// IsNotImplemented returns true if the error is due to not being implemented
 func IsNotImplemented(err error) bool {
 	return errors.Cause(err) == ErrNotImplemented
 }

errdefs/grpc.go

@@ -53,6 +53,7 @@ func ToGRPCf(err error, format string, args ...interface{}) error {
 	return ToGRPC(errors.Wrapf(err, format, args...))
 }
 
+// FromGRPC returns the underlying error from a grpc service based on the grpc error code
 func FromGRPC(err error) error {
 	if err == nil {
 		return nil