fix typo resultin in dist/distcheck problem
diff --git a/src/Makefile.am b/src/Makefile.am
index 2e2eaf0..1a7d87f 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1,4 +1,4 @@
-SUBDRIS=vty
+SUBDIRS=vty
 
 # This is _NOT_ the library release version, it's an API version.
 # Please read Chapter 6 "Library interface versions" of the libtool documentation before making any modification