Fix xml syntax in shadow texture size tutorial (backport #3111)

[mergify]

🦟 Bug fix

Summary

Fixes xml syntax error.

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
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This is an automatic backport of pull request #3111 done by [Mergify](https://mergify.com).

[iche033]

@Mergifyio rebase

[mergify]

rebase

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