Refactored P4 test

A more descriptive name is put to the p4 test so as to leave space for additional tests coming soon. This test applies L1 forwarding between a P4 switch's ports, thus the new name of this test is set accordingly.

Closes issue #219 (closed)

src/tests/p4-fwd-l1/README.md

@@ -39,7 +39,7 @@ In the `./mininet/` directory there are different mininet topology examples. The
 
 ## P4 artifacts
 
-In the `./p4/` directory there are the compiled p4 artefacts that contain the pipeline that will be pushed to the p4 switch, along with the p4-runtime definitions. 
+In the `./p4/` directory there are compiled p4 artefacts of the pipeline that will be pushed to the p4 switch, along with the p4-runtime definitions.
 The `./setup.sh` script copies from this directory. So if you need to change p4 program, make sure to put the compiled artefacts here.
 
 ## Latency probe