refactor(SKILL.md): update description for clarity and comprehensiveness of coding standards

skills/coding-standard-rules/SKILL.md

@@ -1,6 +1,6 @@
 ---
 name: coding-standard-rules
-description: Coding standard rules for writing clean, maintainable, consistent code and review.
+description: "Mandatory coding standards (function size, naming, no magic values, guard clauses, error handling, secrets, code reuse, comments). Use whenever writing, editing, refactoring, or reviewing source code in any language, even one-line changes; load it before writing the first line of code."
 ---
 
 ## Code Writing Rules