docs: add missing backtick (vuejs#2302)

Add a single backtick causing code rendering issue

Author: mael-belval

packages/docs/guide/essentials/route-matching-syntax.md

@@ -117,7 +117,7 @@ Note that `*` technically also marks a parameter as optional but `?` parameters
 If the route segment contains more than **just an optional parameter**, it won't match a path **without the trailing slash**. For example:
 
 - `/users/:uid?-:name?` won't match `/users`, only `/users/-` or even `/users/-/`
-- `/users/:uid(\\d+)?:name? won't match `/users`, only `/users/`, `/users/2`, `/users/2/`, etc
+- `/users/:uid(\\d+)?:name?` won't match `/users`, only `/users/`, `/users/2`, `/users/2/`, etc
 
 You can play around with the matching syntax [in the playground](https://paths.esm.dev/?p=AAMsIPQg4AoKzidgQFoEXAmw-IEBBRYYOE0SkABTASiz1qgBpgQA1QTsFjAb3h2onsmlAmGIFsCXjXh4AIA.&t=/users/2/#)