doc/ref/spec.md: reformat to deal with Hugo bug
Change-Id: Id006aa7ffea6050b89319cfe71d6517e834db37a
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/4942
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>
diff --git a/doc/ref/spec.md b/doc/ref/spec.md
index c1fc803..300e5d9 100644
--- a/doc/ref/spec.md
+++ b/doc/ref/spec.md
@@ -1050,10 +1050,20 @@
single field.
As the latter case is common, a concrete label followed by
a question mark `?` may be used as a shorthand.
-So `foo?: bar` is a shorthand for `["foo"]: bar`.
+So
+```
+foo?: bar
+```
+is a shorthand for
+```
+["foo"]: bar
+```
The question mark is not part of the field name.
The token `...` may be used as the last declaration in a struct
-and is a shorthand for `[_]: _`.
+and is a shorthand for
+```
+[_]: _
+```
Concrete field labels may be an identifier or string, the latter of which may be
interpolated.
