doc: avoid warning on missing arv_g_type_init doc.
doc: avoid warning on missing arv_g_type_init doc.

AnilRamachandran/aravis,AravisProject/aravis,AnilRamachandran/aravis,AravisProject/aravis,AnilRamachandran/aravis,AravisProject/aravis,AnilRamachandran/aravis,AravisProject/aravis,AravisProject/aravis,AnilRamachandran/aravis