correct nesting for included jars

spec/fmt.md

@@ -39,9 +39,9 @@ loading_type = "required" # the type 'required' is implicit if it isn't present.
 These keys are automatically inserted by [Phytotelma](/contributing/tools#phytotelma) for generated metadata files and their host mods respectively.
 You should never need to insert them yourself.
 ```toml
-included_jars = [
+included_jars = [[
     { id = "mod_id", path = "META-INF/jars/mod.jar" }
-]
+]]
 phytotelma.generated = true 
 
 ```