Fix license not detected correctly by Github

LICENSE

@@ -12,9 +12,9 @@ notice, this list of conditions and the following disclaimer.
 copyright notice, this list of conditions and the following disclaimer
 in the documentation and/or other materials provided with the
 distribution.
-   * Neither the name of Andreas Krennmair, Google, nor the names of its
-contributors may be used to endorse or promote products derived from
-this software without specific prior written permission.
+   * Neither the name of the copyright holder nor the names of
+its contributors may be used to endorse or promote products derived
+from this software without specific prior written permission.
 
 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

main.go

@@ -4,7 +4,7 @@
 // Use of this source code is governed by a BSD-style license
 // that can be found in the LICENSE file in the root of the source
 // tree.
-//
+// SPDX-Licence-Identifier: BSD-3-Clause
 
 package gopacket_gtp
 
@@ -118,7 +118,7 @@ func (g *GTPv1U) SerializeTo(b gopacket.SerializeBuffer, opts gopacket.Serialize
 	if g.ExtensionHeaderFlag || g.SequenceNumberFlag || g.NPDUFlag {
 		extHeadersLen += 4
 		for _, eh := range g.GTPExtensionHeaders {
-			extHeadersLen += len(eh.Content) + 2 // 2 bytes for Type + Lenght
+			extHeadersLen += len(eh.Content) + 2 // 2 bytes for Type + Length
 
 		}
 	}