Update Vue3 and Nuxt.js integration guide

[manniL]

Right now, https://purgecss.com/guides/nuxt.html and https://purgecss.com/guides/vue.html are for v2 of both frameworks. Integration for Vue3 has changed only based on the "defaults", for Nuxt, I've updated the module which comes with several changes as well

[github-actions]

This issue is stale because it has been open 90 days with no activity. Remove stale label or comment or this will be closed in 5 days.

[darkvertex]

Not stale. Docs need love.

[github-actions]

This issue is stale because it has been open 90 days with no activity. Remove stale label or comment or this will be closed in 5 days.

[manniL]

Not stale. Docs need love.

^

[lucasuracosta]

^