This documentation is not using the current rendering mechanism and is probably outdated. The extension maintainer should switch to the new system. Details on how to use the rendering mechanism can be found here.
Default value is Hash and it is useful if you want to have an exact validation on the script. It means it will validate the whole content. I recommend this way if you have only some inline script blocks.
Nonce on the other hand is useful if you have many script parts. It works like a simple entrance control system. Every script with the given pass could go through. The pass (=nonce) will be generated newly each time the page is being generated. It is NOT recommended with a long caching lifetime for the page. (It could be bypassed then) Of course it works ell with the standard one day (or lower) principe.