docs: document the {' '} trick

documentation/docs/07-misc/07-v5-migration-guide.md

@@ -682,6 +682,14 @@ Previously, Svelte employed a very complicated algorithm to determine if whitesp
 
 - Whitespace between nodes is collapsed to one whitespace
 - Whitespace at the start and end of a tag is removed completely
+
+  This new behavior is slightly different from native HTML rendering. For example, `<p>foo<span> - bar</span></p>` will render:
+
+  - `foo - bar` in HTML
+  - `foo- bar` in Svelte 5
+
+  You can reintroduce the missing space by including it explicitly: `<p>foo<span>{' '}- bar</span></p>`
+
 - Certain exceptions apply such as keeping whitespace inside `pre` tags
 
 As before, you can disable whitespace trimming by setting the `preserveWhitespace` option in your compiler settings or on a per-component basis in `<svelte:options>`.