Collecting Athena tutorial links to the front page

This collects together all of the links to practical materials shown during the Athena tutorial and collects them onto the front page for the tutorial - some are internal links whereas others point to GitLab or the Twiki. Some links will need to be updated as more material is migrated.

added 1 commit

• 29c81c08 - Adding stubs for external links (Twiki, GitLab) and removing unnecessary text

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added 1 commit

• aabb64a6 - Adding stubs for configuration and VSCode tutorials (which are on this site...

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resolved all threads

mentioned in commit 7a38615e

merged