[doc_checker] Update docs project

The docs folder now lives in //fuchsia

Bug: DNO-417 #comment
Change-Id: I91ef9268f6afba82aadbc3c6cf6f551b1dc05ded
diff --git a/tools/doc_checker/bin/main.dart b/tools/doc_checker/bin/main.dart
index 877d685..650dee5 100644
--- a/tools/doc_checker/bin/main.dart
+++ b/tools/doc_checker/bin/main.dart
@@ -86,7 +86,7 @@
     ..addOption(
       _optionGitProject,
       help: 'Name of the Git project hosting the documentation directory',
-      defaultsTo: 'docs',
+      defaultsTo: 'fuchsia',
     );
   final ArgResults options = parser.parse(args);