fix typo

src/vs/platform/files/common/fileService.ts

@@ -362,7 +362,7 @@ export class FileService extends Disposable implements IFileService {
 		// mtime and etag, we bail out to prevent dirty writing.
 		//
 		// First, we check for a mtime that is in the future before we do more checks. The assumption is
-		// that only the mtime is an indicator for a file that has changd on disk.
+		// that only the mtime is an indicator for a file that has changed on disk.
 		//
 		// Second, if the mtime has advanced, we compare the size of the file on disk with our previous
 		// one using the etag() function. Relying only on the mtime check has prooven to produce false