document [x+2e]well-known pattern - closes #7659

documentation/docs/30-advanced/10-advanced-routing.md

@@ -160,6 +160,8 @@ src/routes/🤪/+page.svelte
 
 The format for a Unicode escape sequence is `[u+nnnn]` where `nnnn` is a valid value between `0000` and `10ffff`. (Unlike JavaScript string escaping, there's no need to use surrogate pairs to represent code points above `ffff`.) To learn more about Unicode encodings, consult [Programming with Unicode](https://unicodebook.readthedocs.io/unicode_encodings.html).
 
+> Since TypeScript [struggles](https://github.com/microsoft/TypeScript/issues/13399) with directories with a leading `.` character, you may find it useful to encode these characters when creating e.g. [`.well-known`](https://en.wikipedia.org/wiki/Well-known_URI) routes: `src/routes/[x+2e]well-known/...`
+
 ### Advanced layouts
 
 By default, the _layout hierarchy_ mirrors the _route hierarchy_. In some cases, that might not be what you want.