Move or replicate guides into Pwning OWASP Juice Shop

[bkimminich]

Currently, Multi-Juicer is only mentioned in the Trainer's guide chapter of the ebook/documentation. It should definitely receive its own chapter now that it is an official part of the Juice Shop family. It could then also be considered to move/replicate the full guides into the ebook and just keep a shorter version in the repo docs/readme itself. Alternatively the Multi-Juicer chapter could refer to the existing guides, but this would be the opposite approach of the other Juice Shop components, where the long version is in the ebook and the short one in the repos as seen below:

https://github.com/juice-shop/juice-shop#setup

https://github.com/juice-shop/juice-shop-ctf#setup----

[bkimminich]

For the time being I've added just links to the guide directories, but I think eventually the better location would be https://github.com/juice-shop/pwning-juice-shop/blob/develop/docs/modules/ROOT/pages/part4/multi-juicer.adoc itself, despite being "further away" from the code. It makes the guides accessible directly in the main docs and the available book formats, where jumping to external (from the book's perspective) resources results in a less constant reading flow.

[AnmolSirola]

@bkimminich In the previous commit, you replicated the multi-juicer guide in the ebook repository, and this is now reflected in the Hosting Platform for Multiple Users chapter of the book.

Moving forward, can you guide me to what other elements remain to be replicated in the ebook from the multi-juicer guide?

I am looking forward to contributing to this issue. :)