Fix typo in reference.md

diff --git a/src/doc/reference.md b/src/doc/reference.md
index 1d27ac096df8a9190acbd66740dd15cbb6d2e580..47c25548af0ce5baaad773a22fb66f3a9e6aee85 100644 (file)
--- a/src/doc/reference.md
+++ b/src/doc/reference.md
@@ -522,7 +522,7 @@ The two values of the boolean type are written `true` and `false`.
 ### Symbols
 
 ```{.ebnf .gram}
-symbol : "::" "->"
+symbol : "::" | "->"
        | '#' | '[' | ']' | '(' | ')' | '{' | '}'
        | ',' | ';' ;
 ```