reformat some sentences

docs/developer/code-style.md

 # Developer - Code style
 
-- Variable names should alway be in *camelCase* and do **not** start with a capital letter
-- Class names should alway be in *CamelCase* and do **always** start with a capital letter
-- Avoid using null, the Option type in scala can be used instead
-- If a method/value is designed to be overridden make it a `def` and override it with a `def`, do not use `val`
\ No newline at end of file
+## General rules
+- Variable names should alway be in *CamelCase* and does **not** start with a capital letter
+- Class names should alway be in *CamelCase* and does **always** start with a capital letter
+- Avoid using `null`, the Option `type` in Scala can be used instead
+- If a method/value is designed to be overridden make it a `def` and override it with a `def`, we encourage you to not use `val`
\ No newline at end of file