New boxart links (Polprzewodnikowy#135)

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## Description
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Improve the gamepak boxart links with better sprite matching.

## Motivation and Context
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Games were not always matched correctly.
Works towards a boxart pack for every region of every game.

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## Types of changes
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- [ ] Improvement (non-breaking change that adds a new feature)
- [ ] Bug fix (fixes an issue)
- [ ] Breaking change (breaking change)
- [x] Documentation Improvement
- [ ] Config and build (change in the configuration and build system,
has no impact on code or features)

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- [ ] My code follows the code style of this project.
- [ ] My change requires a change to the documentation.
- [ ] I have updated the documentation accordingly.
- [ ] I have added tests to cover my changes.
- [ ] All new and existing tests passed.

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Signed-off-by: GITHUB_USER <GITHUB_USER_EMAIL>

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Co-authored-by: Robin Jones <[email protected]>

README.md

@@ -84,9 +84,10 @@ i.e.
 
 
 As a starting point, here are some links to boxart packs:
-* [American GamePak Boxart](https://mega.nz/file/6cNGwSqI#8X5ukb65n3YMlGaUtSOGXkKo9HxVnnMOgqn94Epcr7w)
-* [European GamePak Boxart](https://mega.nz/file/O7AjDbRJ#VnVU10dq8HQvBUQptppI6PAcQMb8-Zembqav8WtAQ_M)
-* [64DD Boxart](https://mega.nz/file/O3JzwD7B#BYl1aV-pbrJ-MxWUbM_K0yGVIRbmSoxJJZqQInRzZyM)
+* [Japan Boxart](https://mega.nz/file/KyJR0B6B#ERabLautAVPaqJTIdBSv4ghbudNhK7hnEr2ZS1Q6ub0)
+* [American Boxart](https://mega.nz/file/rugAFYSQ#JHfgCU2amzNVpC4S6enP3vg--wtAAwsziKa7cej6QCc)
+* [European Boxart](https://mega.nz/file/OmIV3aAK#kOWdutK1_41ffN64R6thbU7HEPR_M9qO0YM2mNG6RbQ)
+* [64DD Boxart](https://mega.nz/file/ay5wQIxJ#k3PF-VMLrZJxJTr-BOaOKa2TBIK7c2t4zwbdshsQl40)
 
 
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