Improve Lighthouse SEO and A11y Rating

[KevSlashNull]

This PR improves the SEO and accessibility score in the Lighthouse rating for the index page.

It mostly just adds alt tags to the images used on the index page but also an aria-label and texts only for screen readers.

The accessibility is not on 100% because your brand color/#f6005c doesn‘t have enough contrast with the white background:

Relates to #49. The performance on www.stormkit.io seems to be worse than in my test env, possibly because of tawk and GTM, or my older MacBook Air. 🤷

Screenshots

	Before	After
Screenshot
Scores	Performance: 29, A11y: 73, Best Pract.: 100, SEO: 89	∆Performance: 0, ∆A11y: +25, ∆Best Pract.: 0, ∆SEO: +11

Both tests were done in the dev environment, however, the performance increased to 98 when pre-building resources and serving via `yarn start. Also, the other scores did not change.

LH report with pre-built resources

[stormkit-io]

Deployment completed

This pull request was successfully built on Stormkit. You can preview it using the following link.

https://stormkit-20328112256009.stormkit.dev ✅

[svedova]

Oh wow Kev you're everywhere :)) This is amazing, thanks a lot for the help 💯 🥇