Description

This:

• adds a new page called Rendering Modes replace the intro content on the SSR page
• updates the sidebar nav to show Rendering Modes
• moves the existing content about improving page performance via streaming to a separate Recipe
• updates links on other docs pages if/as necessary depending on whether we want to link to a conceptual page or adding an adapter (also, probably updated headings even if pointing to the same page)

For future follow up (because it will touch a lot of pages):

• replace existing text "SSR" (e.g. SSR mode, SSR adapters) to "server", "server-rendered", "on-demand rendered" etc. per the context.
• check for older docs that only refer to server mode, because that's all there was when they were written!
• consider renaming this page

PURPOSE:

• The new "basics" page describes Astro's rendering modes (output: 'static', output: 'hybrid', and output: 'server') together all on a new page titled Rendering Modes.
• This and a revamped SSR page (file-name to potentially change to on-demand-rendering but later, for less disruption) also leans into the phrases "pre-rendering" and "on-demand rendering" while downplaying SSG/SSR

Previously, we had

• no real information at all about static, pre-rendering, because that's just what Astro "was".
• only an SSR page that was not significantly refreshed since it was an experimental feature, and had grown by patchwork additions rather than being a united page

Therefore, we often had to describe the difference between all these modes in support threads, including when and why you might choose to use them.

The emphasis here shifts from "a page about SSR" to a core concepts page describing and comparing the three output modes and then a page about enabling server and hybrid as an "add on"

Direct preview link to the new page: https://deploy-preview-4667--astro-docs-2.netlify.app/en/core-concepts/rendering-modes/ and revamped SSR page: https://deploy-preview-4667--astro-docs-2.netlify.app/en/guides/server-side-rendering/