update modules

Author: mertcandav

src/packages/modules/specification.md

@@ -12,4 +12,8 @@ module mylib
 ```
 In the example above, the module name is specified as `mylib`.
 
-A module name may only consist of letters, digits, `_`, or `.` characters. The first character must be either a letter or an `_`.
+A module name may only consist of letters, digits, `_`, or `.` characters. The first character must be either a letter or an `_`.
+
+::: warning
+The `std` is a reserved name and cannot be used for modules as a name.
+:::