doc: link to addons from graphical index

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@69591 15284696-431f-4ddb-bdfa-cd5b030d7da7

man/build_graphical_index.py

@@ -105,6 +105,7 @@ index_items = [
     ('https://grass.osgeo.org/grass73/manuals/libpython/index.html', std_img_name('python'), 'Python'),
     ('https://grass.osgeo.org/programming7/', std_img_name('c'), 'C library'),
     ('manual_gallery.html', std_img_name('gallery'), 'Gallery'),
+    ('http://grass.osgeo.org/grass70/manuals/addons/', std_img_name('addons'), 'Addons'),
 ]