[docs] prerendering adjustments (#6577)

- add the file ending, which should make it more clear where to put things (even if some use .ts, they'll get the idea)
- remove obsolete config

Closes #6538

.changeset/blue-wombats-shake.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-static': patch
+---
+
+[docs] more specific error message when prerendering fails

documentation/docs/11-page-options.md

@@ -15,7 +15,7 @@ It's likely that at least some routes of your app can be represented as a simple
 export const prerender = true;
 ```
 
-Alternatively, you can set `export const prerender = true` in your root `+layout` and prerender everything except pages that are explicitly marked as _not_ prerenderable:
+Alternatively, you can set `export const prerender = true` in your root `+layout.js` or `+layout.server.js` and prerender everything except pages that are explicitly marked as _not_ prerenderable:
 
 ```js
 /// file: +page.js/+page.server.js/+server.js

documentation/docs/14-configuration.md

@@ -56,7 +56,6 @@ const config = {
 		prerender: {
 			concurrency: 1,
 			crawl: true,
-			default: false,
 			enabled: true,
 			entries: ['*'],
 			onError: 'fail',
@@ -260,7 +259,6 @@ See [Prerendering](/docs/page-options#prerender). An object containing zero or m
 
 - `concurrency` — how many pages can be prerendered simultaneously. JS is single-threaded, but in cases where prerendering performance is network-bound (for example loading content from a remote CMS) this can speed things up by processing other tasks while waiting on the network response
 - `crawl` — determines whether SvelteKit should find pages to prerender by following links from the seed page(s)
-- `default` — set to `true` to prerender encountered pages not containing `export const prerender = false`
 - `enabled` — set to `false` to disable prerendering altogether
 - `entries` — an array of pages to prerender, or start crawling from (if `crawl: true`). The `*` string includes all non-dynamic routes (i.e. pages with no `[parameters]` )
 - `onError`

packages/adapter-static/index.js

@@ -27,7 +27,7 @@ export default function (options) {
 				if (dynamic_routes.length > 0) {
 					const prefix = path.relative('.', builder.config.kit.files.routes);
 					builder.log.error(
-						`@sveltejs/adapter-static: all routes must be fully prerenderable (unless using the 'fallback' option — see https://github.com/sveltejs/kit/tree/master/packages/adapter-static#spa-mode). Try adding \`export const prerender = true\` to your root layout — see https://kit.svelte.dev/docs/page-options#prerender for more details`
+						`@sveltejs/adapter-static: all routes must be fully prerenderable (unless using the 'fallback' option — see https://github.com/sveltejs/kit/tree/master/packages/adapter-static#spa-mode). Try adding \`export const prerender = true\` to your root layout.js — see https://kit.svelte.dev/docs/page-options#prerender for more details`
 					);
 					builder.log.error(
 						dynamic_routes.map((id) => `  - ${path.posix.join(prefix, id)}`).join('\n')