[Docs] Obsolete documentation-text regarding target static

[codeflorist]

https://v3.nuxtjs.org/api/configuration/nuxt.config#ssr has the following text:

Whether to enable rendering of HTML - either dynamically (in server mode) or at generate time. If set to false and combined with static target, generated pages will simply display a loading screen with no content.

I believe this is obsolete, because there is no static target option anymore.

[sevillaarvin]

Related https://github.com/nuxt/framework/issues/7753