fix(docs) :: remove unsupported distinct example

examples/official-site/sqlpage/migrations/77_facet.sql

@@ -20,10 +20,11 @@ select ''facet'' as component,
     ''Category'' as description,
     sqlpage.link(sqlpage.path(), json_object(''category'', null)) as all_link,
     $category is null as all_active;
-select distinct category as title,
+select category as title,
     sqlpage.link(sqlpage.path(), json_object(''category'', category)) as link,
     category = $category as active
 from my_table
+group by category
 order by category;
 ```
 ', '0.46.0');

src/webserver/database/sql.rs

@@ -621,6 +621,17 @@ mod tests {
         assert!(query.must_buffer_rows());
     }
 
+    #[test]
+    fn documented_facet_query_is_accepted() {
+        let stmt = one("select category as title, \
+             sqlpage.link(sqlpage.path(), json_object('category', category)) as link, \
+             category = $category as active from my_table group by category order by category");
+        assert!(
+            !matches!(stmt, FileStatement::Error(_)),
+            "the documented facet query must parse"
+        );
+    }
+
     #[test]
     fn static_simple_select_has_no_database_query() {
         let FileStatement::Query(Query {