Local Multiway System research page (#405)

## Changes
* Closes #334.
* Adds a research page explaining how the local multiway system works, and showing some examples for both match-all and spacelike multiway systems.

## Comments
* This is a "living" document, and it will be improved in future PRs. Anybody can contribute, even if they are not the original author. For example, it will be updated once the progress is done on local isomorphism (see future research section).
* The purpose of this pull request is essentially a peer-review of this bulletin. Feel free to leave comments for both the physics content, the system description, as well as small/technical comments about the explanation.
* If you are not a *SetReplace* collaborator, you can still comment below.

## Examples
* Read the [rendered version](https://github.com/maxitg/SetReplace/blob/localMultiwaySystemNote/Research/LocalMultiwaySystem/LocalMultiwaySystem.md).

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