docs: use gh alert syntax for callouts

Signed-off-by: David Karlsson <35727626+dvdksn@users.noreply.github.com>

docs/reference/buildx_inspect.md

@@ -43,8 +43,7 @@ name of the builder to inspect to get information about that builder.
 The following example shows information about a builder instance named
 `elated_tesla`:
 
-> **Note**
->
+> [!NOTE]
 > The asterisk (`*`) next to node build platform(s) indicate they have been
 > manually set during `buildx create`. Otherwise the platforms were
 > automatically detected.