[gnome-documents] build: Unbreak 'make distcheck'

[Debarshi Ray <debarshir src gnome org>]

commit 7539efe474ceba48c53d1c8b3cd3fddcff74008b
Author: Debarshi Ray <debarshir gnome org>
Date:   Mon Mar 12 13:41:48 2018 +0100

    build: Unbreak 'make distcheck'
    
    Fallout from 759f193b62f363d312740d43a1453f8d8d3b0a0b
    
    https://bugzilla.gnome.org/show_bug.cgi?id=787013

 data/icons/Makefile.am |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/data/icons/Makefile.am b/data/icons/Makefile.am
index cf2f2af..73b8c2d 100644
--- a/data/icons/Makefile.am
+++ b/data/icons/Makefile.am
@@ -55,6 +55,7 @@ EXTRA_DIST = \
        $(public_16x16_icons_DATA)      \
        $(public_22x22_icons_DATA)      \
        $(public_24x24_icons_DATA)      \
+       $(public_32x32_icons_DATA)      \
        $(public_48x48_icons_DATA)      \
        $(public_256x256_icons_DATA)    \
        $(public_512x512_icons_DATA)    \