Add how to override modules to documentation

[OliverKK]

[nbauernfeind]

This is done the same way it is in Java.

See Modules.override in the javadocs.

Or a more specific stackoverflow answer.

[OliverKK]

I thought it might be handy to have an example of it within the readme though.
Since override and with are reserved, these methods must be written in backticks.

Modules.`override`(new BaseModule).`with`(new TestModule)

[nbauernfeind]

Great Point =).