Update links + stats

[mesram]

Link to the new docs, old link basically just landed on the createContext function which is a weird place to take newbies.
Cleanup the link to the playground.
Change SolidHack 2022 reference to 2024.
Update the stats for bundle size, GitHub stars, and age.

[mesram]

Bundle size in bundle phobia is 3.9kb, but I've put it as 4 in all the non-English languages in order to avoid needing to deal with decimal formatting.

[atk]

bundle phobia will bundle the non-reactive server package from what I have seen, which is not really indicative of the actual client library size.

$ terser node_modules/solid-js/dist/solid.js | gzip -9 | wc -c
10488
$ terser node_modules/solid-js/store/dist/store.js | gzip -9 | wc -c 
3034

So it is 10kb without stores and another 3kb for the stores.