Enable RON syntax highlighting

Author: Naseschwarz

THEMES.md

@@ -18,7 +18,7 @@ Alternatively, you can create a theme in the same directory mentioned above and
 
 Example theme override:
 
-```
+```ron
 (
     selection_bg: Some("Blue"),
     selection_fg: Some("#ffffff"),
@@ -39,14 +39,14 @@ Notes:
 The syntax highlighting theme can be defined using the element `syntax`. Both [default themes of the syntect library are supported](https://github.com/trishume/syntect/blob/7fe13c0fd53cdfa0f9fea1aa14c5ba37f81d8b71/src/dumps.rs#L215) and custom themes are supported.
 
 Example syntax theme:
-```
+```ron
 (
     syntax: Some("InspiredGitHub"),
 )
 ```
 
 Custom themes are located in the [configuration directory](#configuration), are using TextMate's theme format and must have a `.tmTheme` file extension. To load a custom theme, syntax must be set to the name without the file extension. For example, to load [`Blackboard.tmTheme`](https://raw.githubusercontent.com/filmgirl/TextMate-Themes/refs/heads/master/Blackboard.tmTheme), place the file next to `theme.ron` and set:
-```
+```ron
 (
     syntax: Some("Blackboard"),
 )
@@ -58,15 +58,15 @@ Custom themes are located in the [configuration directory](#configuration), are
 
 If you want to change how the line break is displayed in the diff, you can also specify `line_break` in your `theme.ron`:
 
-```
+```ron
 (
     line_break: Some("¶"),
 )
 ```
 
 Note that if you want to turn it off, you should use a blank string:
 
-```
+```ron
 (
     line_break: Some(""),
 )