typo fix and restructure of one line

docs/code_style.md

@@ -107,8 +107,8 @@ $config = array(
 - Classes should be named using `CamelCase`.
 - The brace should always be written on the line underneath the class name.
 - Every class must have a documentation block that conforms to the PHPDoc.
-- All code in a class must be indented with a signle tab.
-- Only one class is permitted per PHP file.
+- All code in a class must be indented with a single tab.
+- There should be only one class in a single PHP file.
 - All classes should be namespaced.
 - Class name should match file name. Class namespace should match directory structure.