Fix lint error

Buildifier complains about error in asciidoc.bzl

Change-Id: Id826f5393b94d56905c37e1c75ad6ac223296666
diff --git a/tools/bzl/asciidoc.bzl b/tools/bzl/asciidoc.bzl
index f3c4646..1e7ec96 100644
--- a/tools/bzl/asciidoc.bzl
+++ b/tools/bzl/asciidoc.bzl
@@ -1,7 +1,7 @@
 def documentation_attributes():
     return [
         "toc2",
-        'newline="\\n"',
+        "newline=\"\\n\"",
         'asterisk="*"',
         'plus="+"',
         'caret="^"',