[gdk-pixbuf] build: Update the description of the gtk_doc option

[Emmanuele Bassi <ebassi src gnome org>]

commit 841d2bf1eab4f11e266199d00ea9fd81e94f6830
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Sun Mar 21 15:00:48 2021 +0000

    build: Update the description of the gtk_doc option
    
    We don't require gtk-doc.

 meson_options.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meson_options.txt b/meson_options.txt
index 930f3bdf8..b6d82e9b6 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -15,7 +15,7 @@ option('builtin_loaders',
        type: 'string',
        value: 'none')
 option('gtk_doc',
-       description: 'Whether to generate the API reference (requires GTK-Doc)',
+       description: 'Whether to generate the API reference',
        type: 'boolean',
        value: false)
 option('docs',