changed doc install dir to match FHS (/usr/share/doc/)

git-svn-id: http://svn.xiph.org/trunk/ao@863 0101bb08-14d6-0310-b084-bc0e0c8e3800

doc/Makefile.am

@@ -2,7 +2,7 @@
 
 AUTOMAKE_OPTIONS = foreign
 
-docdir = $(prefix)/doc/$(PACKAGE)-$(VERSION)
+docdir = $(datadir)/$(PACKAGE)-$(VERSION)
 
 doc_DATA = API USAGE DRIVERS WANTED