[book] Minor patch to conventions - module names snake_case

language/documentation/book/src/coding-conventions.md

@@ -10,7 +10,7 @@ This section lays out some basic coding conventions for Move that the Move team
 - **Constant names**: should be upper camel case and begin with an `E` if they represent error codes (e.g., `EIndexOutOfBounds`) and upper snake case if they represent a non-error value (e.g., `MIN_STAKE`).
 -
 - **Generic type names**: should be descriptive, or anti-descriptive where appropriate, e.g., `T` or `Element` for the Vector generic type parameter. Most of the time the "main" type in a module should be the same name as the module e.g., `option::Option`, `fixed_point32::FixedPoint32`.
-- **Module file names**: should be the same as the module name e.g., `Option.move`.
+- **Module file names**: should be the same as the module name e.g., for `std::option` use `option.move`.
 - **Script file names**: should be lower snake case and should match the name of the “main” function in the script.
 - **Mixed file names**: If the file contains multiple modules and/or scripts, the file name should be lower snake case, where the name does not match any particular module/script inside.