Add EFGs from Shoham and Leyton-Brown (2008)

[wyz2368]

Thanks for contributing to Gambit! Before you submitting or reviewing a pull request, check out our guidelines for contributing.

The person submitting the PR should ensure it has an informative title and update the headers below, before marking the PR as ready for review and assigning reviewers.

Issues closed by this PR

Add any issues that are being closed by this PR to the list. Use "Closes" or another keyword followed by the issue number.

• Closes #ISSUE_NUMBER

Description of the changes in this PR

Update the description of the changes made in this PR. You can delete this section if the changes are already fully described in the linked issues.

This PR ...

How to review this PR

The gambit repository contains source code and documentation for several different components. Explain how a reviewer should approach reviewing the specific changes made in this PR.

For example, you might include instructions like:

• "Review code changes and ensure tests cover edge cases"
• "Rebuild the GUI from this branch, then test features X, Y, Z work as expected"
• "Click the link to the documentation page and sense check by reading"

[rahulsavani]

This looks good at a glance but to properly review it, please first:

• merge in master to your fork so that the entry ShoLeyB08 is in the bibtex
• please update build_support/catalog/catalog_hierarchy.yaml as per the instructions at at https://gambitproject.readthedocs.io/en/latest/developer.catalog.html#updating-catalog, where the latest is important in many cases.

[rahulsavani]

Three things:

1. Citations are empty

The problem is the missing ref ([] instead of [ShoLeyB08]). I am not sure of the reason but one immediate thing I noticed is that the category is missing in the bibitem. Compare the following two, where the second has a category of textbooks:

@book{ShoLeyB08,
title={Multiagent systems: Algorithmic, game-theoretic, and logical foundations},
author={Shoham, Yoav and Leyton-Brown, Kevin},
year={2008},
publisher={Cambridge University Press}
}

with

@book{vS22,
author = {von Stengel, B.},
title = {Game Theory Basics},
publisher = {Cambridge University Press},
year = {2022},
category = {textbooks}
}

Hopefully the actual citation will appear when you add the category -- in any case, we want to make sure the final entry looks good before submitting the PR, which it didn't in this case.

2. Names inconsistent with existing entries

Please use naming that is totally consistent with what is already in the catalog. So fig5_1.efg instead of MAS_Fig5_1.efg (the MAS is anyway redundant -- the slug aleady mentions this, and the file contents give the citation, so not need for an extra indicator in the filename given that it's in the folder name).

3. Explicit .ef files

You have included .ef files in the PR. That might be fine, but I wanted to make sure these are not just the ones created by draw_tree anyway -- generally we are not adding .ef files unless they significantly differ from what we can create with draw_tree, e.g., if you did some manual edits to the .ef. If there are manual edits, it's fine to keep these, otherwise, let's remove them from the PR like for most other books/papers where entries are just the .efg.

Please request a re-review when appropriate, so that I know you are happy with it from your side.