Updated docs: contributors

[timlichtenberg]

Description

Contributor updates:

• Updated Harrison Nicholls' email address to h-nicholls@pm.me in docs/index.md
• Added Oliver Shorttle with email os258@cam.ac.uk to the contributors table in docs/index.md

Checklist

• I have followed the contributing guidelines
• My code follows the style guidelines of this project
• I have performed a self-review of my code
• My changes generate no new warnings or errors
• I have checked that the tests still pass on my computer
• I have updated the docs, as appropriate
• I have added tests for these changes, as appropriate
• I have checked that all dependencies have been updated, as required

[Copilot]

Pull request overview

This PR updates the contributors table in the documentation by modifying an existing contributor's contact information and adding a new contributor.

Changes:

• Updated Harrison Nicholls' email address from institutional to personal email
• Added Oliver Shorttle as a new contributor with Cambridge email address

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