docs(configuration): change //@ sourceURL to //# sourceURL (#6215)

since `//@ sourceURL` is deprecated

Author: draculapile

src/content/configuration/devtool.mdx

@@ -99,7 +99,7 @@ T> See [`output.sourceMapFilename`](/configuration/output/#outputsourcemapfilena
 
 The following options are ideal for development:
 
-`eval` - Each module is executed with `eval()` and `//@ sourceURL`. This is pretty fast. The main disadvantage is that it doesn't display line numbers correctly since it gets mapped to transpiled code instead of the original code (No Source Maps from Loaders).
+`eval` - Each module is executed with `eval()` and `//# sourceURL`. This is pretty fast. The main disadvantage is that it doesn't display line numbers correctly since it gets mapped to transpiled code instead of the original code (No Source Maps from Loaders).
 
 `eval-source-map` - Each module is executed with `eval()` and a SourceMap is added as a DataUrl to the `eval()`. Initially it is slow, but it provides fast rebuild speed and yields real files. Line numbers are correctly mapped since it gets mapped to the original code. It yields the best quality SourceMaps for development.