doc/ref/spec.md: fix ListLit production
Fixes #823
Change-Id: Ie3bb9f48f36c13ea1a889b5c411b353c39c4690c
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/9001
Reviewed-by: CUE cueckoo <cueckoo@gmail.com>
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>
diff --git a/doc/ref/spec.md b/doc/ref/spec.md
index 7e93cfc..228608c 100644
--- a/doc/ref/spec.md
+++ b/doc/ref/spec.md
@@ -1612,8 +1612,8 @@
and an unlimited number of elements as its upper bound.
```
-ListLit = "[" [ ElementList [ "," [ Ellipsis ] ] [ "," ] ] "]" .
-ElementList = Embedding { "," Embedding } .
+ListLit = "[" [ ElementList [ "," ] ] "]" .
+ElementList = Ellipsis | Embedding { "," Embedding } [ "," Ellipsis ] .
```
Lists can be thought of as structs:
