Better documentation for how to deploy non python lambda functions

[onema]

I started using this module for a Java11 lambda function and I was having a hard time making the lambda function execute as I kept getting an error message saying that my class was not found.

I later realize that the module ZIPs the jar I provided and this causes it to break.

I spent some time looking at the code and I realize that a simple workaround would be to use the build_command property like so:

  build_command = "cp '$source' '$filename' "

Improving the documentation can help with the deployment of functions that do not require to be ZIP, like Java, or are already ZIP.