Fixup some doc and compile issues.

Change-Id: I75547e3fb4e1e4be08bde08f0bcfcf7e979791e7
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/25640
Reviewed-by: dan sinclair <dsinclair@chromium.org>
diff --git a/Doxyfile b/Doxyfile
index a3d64f6..3fcdc96 100644
--- a/Doxyfile
+++ b/Doxyfile
@@ -986,7 +986,7 @@
 # (index.html). This can be useful if you have a project on for instance GitHub
 # and want to reuse the introduction page also for the doxygen output.
 
-USE_MDFILE_AS_MAINPAGE = README.md
+USE_MDFILE_AS_MAINPAGE = ./README.md
 
 #---------------------------------------------------------------------------
 # Configuration options related to source browsing