Clarify caption file naming conventions in documentation

ui/v2.5/src/docs/en/Manual/Captions.md

@@ -8,10 +8,10 @@ Ensure the caption files follow these naming conventions:
 
 ## Scene
 
-- {scene_file_name}.{language_code}.ext
-- {scene_file_name}.ext
+- {scene_file_name}.{language_code}.{ext}
+- {scene_file_name}.{ext}
 
-Where `{language_code}` is defined by the [ISO-6399-1](https://en.wikipedia.org/wiki/List_of_ISO_639-1_codes) (2 letters) standard and `ext` is the file extension. Captions files without a language code will be labeled as Unknown in the video player but will work fine.
+Where `{language_code}` is defined by the [ISO-6399-1](https://en.wikipedia.org/wiki/List_of_ISO_639-1_codes) (2 letters) standard and `{ext}` is the file extension. Captions files without a language code will be labeled as Unknown in the video player but will work fine.
 
 Scenes with captions can be filtered with the `captions` criterion.