Update pfcp-agent value and add explanations to configs

Also remove 'measure' field, which is not used in P4-UPF

Change-Id: I1fb16c81ccf65eab05f34c956518c06e87294534
diff --git a/pfcp-agent/values.yaml b/pfcp-agent/values.yaml
index 1997bfd..c48db95 100644
--- a/pfcp-agent/values.yaml
+++ b/pfcp-agent/values.yaml
@@ -30,15 +30,28 @@
   pfcp:
     cfgFiles:
       upf.json:
-        measure: true
+        log_level: "info"
+
         enable_p4rt: true
         p4rtciface:
-          # Should be the same as s1uAddr in ONOS netcfg for the UP4 app.
+          # N3/S1u address for 5G/4G.
           access_ip: "172.17.0.1/32"
+          # IP and port exposed by UP4 P4Runtime server.
           # Do not change unless you are deploying ONOS in a custom way.
           p4rtc_server: "sdfabric-onos-classic-hs"
           p4rtc_port: "51001"
+          # Identify P4-UPF slice this PFCP agent instance belongs to.
+          # The same slice ID should also be defined in the slicing section of the ONOS netcfg
+          # Optional. Default value is 0.
+          slice_id: 0
+
         cpiface:
+          # IP pool from which we allocate UE IP address
+          ue_ip_pool: "10.250.0.0/24"
+          # Data Network Name. Must be consistent with the one set in ROC.
+          dnn: "internet"
+          # Used to get local IP address and local NodeID in PFCP messages.
+          # Do not change unless you are deploying PFCP agent in a custom way.
           hostname: "pfcp-agent"
 
 service: