fix(docs): change 'countries' to 'characters' to match JS example to data source (supabase#39840)

Author: marsou001

apps/docs/spec/supabase_js_v2.yml

@@ -6571,7 +6571,7 @@ functions:
         code: |
           ```ts
           const { data, error } = await supabase
-            .from('countries')
+            .from('characters')
             .select('name')
             .range(0, 1)
           ```