[gnome-build-meta] sdk/libsoup.bst: switch doc option to gtk_doc

[Claudio Saavedra <csaavedra src gnome org>]

commit e017d59b13169eab1b61c953ce58af042db57b3c
Author: Claudio Saavedra <csaavedra igalia com>
Date:   Thu May 16 16:25:05 2019 +0300

    sdk/libsoup.bst: switch doc option to gtk_doc
    
    This is the GNOME standard and I just fixed it in libsoup so stick
    to it.

 elements/sdk/libsoup.bst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/elements/sdk/libsoup.bst b/elements/sdk/libsoup.bst
index 095c940f..0986e617 100644
--- a/elements/sdk/libsoup.bst
+++ b/elements/sdk/libsoup.bst
@@ -21,4 +21,4 @@ variables:
   meson-local: |
     -Dtls_check=false \
     -Dvapi=true \
-    -Ddocs=true
+    -Dgtk_doc=true