Add spdx license comments 1 (#658)

* Move optional steps for testing VMs out of README.md file
This may help avoid new users being confused that they must follow
those instructions.

Signed-off-by: Andy Fingerhut <andy_fingerhut@alum.wustl.edu>

* Add SPDX-License-Identifier line to most files.
All of the files are Apache 2.0 license.

Signed-off-by: Andy Fingerhut <andy_fingerhut@alum.wustl.edu>

---------

Signed-off-by: Andy Fingerhut <andy_fingerhut@alum.wustl.edu>

Author: jafingerhut

.gitignore

@@ -1,3 +1,5 @@
+# SPDX-License-Identifier: Apache-2.0
+
 # Python byte code
 *.pyc
 *.pyo

CONTRIBUTING.md

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: Apache-2.0
 BMV2_SWITCH_EXE = simple_switch_grpc
 TOPO = pod-topo/topology.json
 

README.md

@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: Apache-2.0
 /* -*- P4_16 -*- */
 #include <core.p4>
 #include <v1model.p4>

exercises/basic/Makefile

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+# SPDX-License-Identifier: Apache-2.0
 import os
 import sys
 

exercises/basic/README.md

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+# SPDX-License-Identifier: Apache-2.0
 import random
 import socket
 import sys

exercises/basic/basic.p4

@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: Apache-2.0
 /* -*- P4_16 -*- */
 #include <core.p4>
 #include <v1model.p4>

exercises/basic/receive.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: Apache-2.0
 BMV2_SWITCH_EXE = simple_switch_grpc
 
 include ../../utils/Makefile