Add lua language specifier for syntax highlighting

How-to-enable-stylistic-sets.md

@@ -82,7 +82,7 @@ font_features FiraCode-Regular +ss01 +ss02 +ss03 +ss04 +ss05 +ss07 +ss08 +zero +
 
 # Wez’s terminal
 
-```
+```lua
 return {
   harfbuzz_features = {"zero" , "ss01", "cv05"}
 }