[babl] meson build: use index_html target name for README file generation

[Øyvind "pippin" Kolås <ok src gnome org>]

commit e73a2c629fce4f64bce59a8346f8087b974807c9
Author: John Marshall <jtm home gmail com>
Date:   Fri Mar 29 09:12:24 2019 +0000

    meson build: use index_html target name for README file generation

 meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index fe8511d..ab28dfd 100644
--- a/meson.build
+++ b/meson.build
@@ -371,7 +371,7 @@ endif
 
 if w3m_bin.found() and build_docs
   custom_target('README',
-    input : [ join_paths('docs', 'index.html'), ] ,
+    input: index_html,
     output: [ 'README' ] ,
     command: [
       w3m_bin,