docs: add note about not modifying exported enum slices

document that StatusValues and StatusNames are exported slices
that should not be modified as this would affect all code using
the enum.

Author: umputun

README.md

@@ -257,6 +257,8 @@ _, err = db.Exec("UPDATE users SET status = ? WHERE id = ?", StatusActive, userI
 
 - **Parsing**: O(1) constant time using map lookup (previously O(n) with switch statement)
 - **Values/Names access**: Zero allocation - returns pre-computed package variables
+
+> **Note**: `StatusValues` and `StatusNames` are exported slices. Do not modify them as this would affect all code using the enum.
 - **Memory efficient**: Single shared instance for each enum value
 - **Declaration order**: Preserved from source code, not alphabetically sorted