added custom syntax highlighting for C3 (only the base)

Author: ulughann

astro.config.mjs

@@ -1,6 +1,7 @@
 import { defineConfig } from "astro/config";
 import tailwind from "@astrojs/tailwind";
 import starlight from "@astrojs/starlight";
+import fs from "node:fs";
 
 // https://astro.build/config
 export default defineConfig({
@@ -12,6 +13,11 @@ export default defineConfig({
     }),
     starlight({
       title: "The C3 Handbook",
+      expressiveCode: {
+        shiki: {
+          langs: [JSON.parse(fs.readFileSync("./c3-grammar.json", "utf-8"))],
+        },
+      },
     }),
   ],
 });