Update links to point to tutorial page

[muffinista]

Addresses processing/p5.js-website#527

Changes:

The link to the page about creating accessible labels is broken and this seems like the proper one.

Screenshots of the change:

PR Checklist

• [x] npm run lint passes
• [x] Inline documentation is included / updated
• [x] Unit tests are included / updated

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[davepagurek]

I think the relative path from / technically will work once it gets merged and then parsed in the website repo, but I think as @perminder-17 suggests, an absolute path probably is the way to go here so that it's easier to test.

[muffinista]

Thanks very much for the feedback! I've switched this to an absolute link, and I properly built/tested locally, and I believe everything is working as expected.