[v6] trailing slash never for endpoints with file extension

src/content/docs/en/guides/upgrade-to/v6.mdx

@@ -89,6 +89,8 @@ Check that both your development environment and your deployment environment are
 
 ### Vite 7.0
 
+<SourcePR number="14445" title="feat: update vite"/>
+
 Astro v6.0 upgrades to Vite v7.0 as the development server and production bundler.
 
 #### What should I do?
@@ -287,6 +289,8 @@ In most cases, the only action needed is to review your existing project's deplo
 
 ### Changed: `i18n.routing.redirectToDefaultLocale` default value
 
+<SourcePR number="14406" title="feat(astro)!: update i18n.redirectToDefaultLocale default"/>
+
 In Astro v5.0, the `i18n.routing.redirectToDefaultLocale` default value was `true`. When combined with the `i18n.routing.prefixDefaultLocale` default value of `false`, the resulting redirects could cause infinite loops.
 
 In Astro v6.0, `i18n.routing.redirectToDefaultLocale` now defaults to `false`. Additionally, it can now only be used if `i18n.routing.prefixDefaultLocale` is set to `true`.
@@ -310,6 +314,25 @@ export default defineConfig({
 
 <ReadMore>Learn more about [Internationalization routing](/en/guides/internationalization/#routing).</ReadMore>
 
+### Changed: endpoints with a file extension cannot be accessed with a trailing slash
+
+<SourcePR number="14457" title="feat!: trailing slash never for endpoints with file extension"/>
+
+In Astro v5.0, endpoints with a pathname ending with a file extension (eg. `/src/pages/sitemap.xml.ts`) could be accessed with a trailing slash (`/sitemap.xml/`) or without (`/sitemap.xml`), no matter the value of `build.trailingSlash`.
+
+In Astro v6.0, these endpoints can only be accessed without a trailing slash.
+
+#### What should I do?
+
+Review your links and remove any referencing an endpoint ending with a file extension and a trailing slash:
+
+```html del={1} ins={2} title="src/pages/index.astro"
+<a href="/sitemap.xml/">Sitemap</a>
+<a href="/sitemap.xml">Sitemap</a>
+```
+
+<ReadMore>Learn more about [`build.trailingSlash`](/en/reference/configuration-reference/#trailingslash).</ReadMore>
+
 ## Breaking Changes
 
 The following changes are considered breaking changes in Astro v5.0. Breaking changes may or may not provide temporary backwards compatibility. If you were using these features, you may have to update your code as recommended in each entry.