Additional files docs with legacyDevProcessCwdBehaviour (#2543)

docs/config/extensions/additionalFiles.mdx

@@ -13,10 +13,11 @@ import { additionalFiles } from "@trigger.dev/build/extensions/core";
 export default defineConfig({
   project: "<project ref>",
   // Your other config settings...
+  // We strongly recommend setting this to false
+  // When set to `false`, the current working directory will be set to the build directory, which more closely matches production behavior.
+  legacyDevProcessCwdBehaviour: false, // Default: true
   build: {
-    extensions: [
-      additionalFiles({ files: ["wrangler/wrangler.toml", "./assets/**", "./fonts/**"] }),
-    ],
+    extensions: [additionalFiles({ files: ["./assets/**", "wrangler/wrangler.toml"] })],
   },
 });
 ```
@@ -25,4 +26,13 @@ This will copy the files specified in the `files` array to the build directory.
 
 This extension effects both the `dev` and the `deploy` commands, and the resulting paths will be the same for both.
 
+If you use `legacyDevProcessCwdBehaviour: false`, you can then do this:
+
+```ts
+import path from "node:path";
+
+// You can use `process.cwd()` if you use `legacyDevProcessCwdBehaviour: false`
+const interRegularFont = path.join(process.cwd(), "assets/Inter-Regular.ttf");
+```
+
 <Note>The root of the project is the directory that contains the trigger.config.ts file</Note>