docs: Add to distribution.
diff --git a/Makefile.am b/Makefile.am
index 61a7ad1..add1089 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -23,16 +23,15 @@
 
 ACLOCAL_AMFLAGS = -I m4
 
-doxygen:
-	cd doxygen && $(MAKE)
-
-.PHONY: doxygen
-
 # Rules for making release tarballs
 
 PACKAGE_DIR = Mesa-$(PACKAGE_VERSION)
 PACKAGE_NAME = MesaLib-$(PACKAGE_VERSION)
 
+EXTRA_DIST = \
+	docs \
+	doxygen
+
 EXTRA_FILES = \
 	aclocal.m4					\
 	configure					\