[doc] Fix typo in docs of vendor tool

Change the code to match the comment.

Signed-off-by: Philipp Wagner <phw@lowrisc.org>
diff --git a/doc/ug/vendor_hw.md b/doc/ug/vendor_hw.md
index 9f3c1f0..21ddd60 100644
--- a/doc/ug/vendor_hw.md
+++ b/doc/ug/vendor_hw.md
@@ -311,7 +311,7 @@
 // section of a .vendor.hjson file
 exclude_from_upstream: [
   // exclude all *.h files in the src directory
-  "src/*.h*",
+  "src/*.h",
   // exclude the src_files.yml file
   "src_files.yml",
   // exclude some_directory and all files below it