Add support for Internationalisation

[mmcky]

Context

Add support for internationalisation for exercise and solution admonitions.

Proposal

No response

Tasks and updates

No response

[douden]

For a temporary fix, you can use the fork https://github.com/TeachBooks/sphinx-exercise by replacing sphinx-exercise by git+https://github.com/TeachBooks/sphinx-exercise.git in your requirements.txt.