Tools: install-prereqs-ubuntu.sh: increase verbosity

Make it a bit more verbose in regard to which script is running, helpful for new user/s especially.

Tools/scripts/install-prereqs-ubuntu.sh

@@ -1,4 +1,5 @@
 #!/bin/bash
+echo "---------- $0 start ----------"
 set -e
 set -x
 
@@ -127,3 +128,4 @@ apt-cache search arm-none-eabi
  git submodule init
  git submodule update
 )
+echo "---------- $0 end ----------"