Added Lua interfae. (Luis Carvalho)
diff --git a/runtime/doc/help.txt b/runtime/doc/help.txt
index 9fe2c6b..79468bb 100644
--- a/runtime/doc/help.txt
+++ b/runtime/doc/help.txt
@@ -158,6 +158,7 @@
 
 Interfaces ~
 |if_cscop.txt|	using Cscope with Vim
+|if_lua.txt|	Lua interface
 |if_mzsch.txt|	MzScheme interface
 |if_perl.txt|	Perl interface
 |if_pyth.txt|	Python interface