doc: report which warnings/errors are new

Signed-off-by: Anas Nashif <anas.nashif@intel.com>
diff --git a/.gitignore b/.gitignore
index 1171bf3..ac73c5a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -31,6 +31,7 @@
 scripts/grub
 doc/reference/kconfig/CONFIG_*
 doc/reference/kconfig/index.rst
+doc/doc.warnings
 tags
 .project
 .cproject