Add examples how to create modules

[rmeissner]

We should provide some documentation/ examples how to write a module

Notes:

• https://gist.github.com/rmeissner/c66371a4b030109cde1020f427122462
• https://gist.github.com/rmeissner/208e35db13d0ebf53b6e35838f1c8122

[tayyabmh]

Hey @rmeissner are these above links up to date? Trying to learn and build a Safe Module on my own as a learning process, but couldn't find great documentation on how to do so.