[babl] docs: add tools dir to dir-overview

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

commit 319d95c282d1780d794572722c7822fc7cfc461f
Author: Øyvind Kolås <pippin gimp org>
Date:   Wed Jun 19 14:27:11 2019 +0200

    docs: add tools dir to dir-overview

 docs/index-static.html.in | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/docs/index-static.html.in b/docs/index-static.html.in
index 17c33a0..9f4d228 100644
--- a/docs/index-static.html.in
+++ b/docs/index-static.html.in
@@ -419,6 +419,7 @@ lab_buffer  = malloc (pixel_count * 3 * sizeof (float));
  │             code from gggl. Finding more exsisting conversions in third
  │             part libraries (hermes, lcms?, liboil?) could improve the
  │             speed of babl.
+ ├──tools      various commandline tools used for verifying accuracy of extensions.
  ├──tests      tests used to keep babl sane during development.
  └──docs       Documentation/webpage for babl (the document you are reading
                originated there.</tt></pre>