fix c error in style guide

style_guide.md

@@ -110,7 +110,7 @@ typedef struct {
 str_t s = {
     .a = 1,
     .b = 2,   // Comma here 
-}
+};
 
 // No trailing commas - only for small and simple structures
 static const str_t y = {.a = 1, .b = 2};