clarify the purpose of the gscriptor scripts

[pmaier-sysmo]

The readme file only says: "With gscriptor, selecting the Virtual PCD enables running the test scripts in ./gscriptor/."

The purpose of those scripts is to provide a debugging environment on a very low level. We basically used them in the early days of softsim where we needed to debug basic functions like SELECT etc. on the lowest level possible by sending hand crafted APDUs individually. Some of the scripts still may contain some hardcoded values that might not fit anymore.

I think we should mention that purpose in the readme file somehow so that users are not confused when the scripts do not work right away. We may also consider to remove the scripts but at least I think they are still good examples to illustrate how to talk to softsim (or eUICCs in general) on a very low level.