add compile info

src/readme.txt

-vppe
+vppe:
+  cd vppe
+
   compile:
     ./pre_install.sh
      make rebuild
+
   run:
      gdb --args  ./build-root/install-vpp_debug-native/vpp/bin/vpp    -c startup_debug.conf
 
 setuniarp:
-    cd  setuniarp;
+   cd  setuniarp
+
+   compile:
     ./compile.sh;
+
+   run:
+     ./arp_run.sh