README: doccument the need of CONFIG_DESKTOP
od: fix help text to include -t
od: handle /proc files (which have filesize 0) correctly
od: fix comments to not lie about return value
od: "%u" is 1 byte less than "%zu"
cat: fix English

diff --git a/include/usage.h b/include/usage.h
index 9ae7d98..dfa7515 100644
--- a/include/usage.h
+++ b/include/usage.h
@@ -2654,10 +2654,10 @@
        "Address:    127.0.0.1\n"
 
 #define od_trivial_usage \
-       "[-aBbcDdeFfHhIiLlOovXx] [FILE]"
+       "[-aBbcDdeFfHhIiLlOovXx] " USE_DESKTOP("[-t TYPE] ") "[FILE]"
 #define od_full_usage \
        "Write an unambiguous representation, octal bytes by default, of FILE\n" \
-       "to standard output. With no FILE, or when FILE is -, read standard input."
+       "to standard output. With no FILE or when FILE is -, read standard input."
 
 #define openvt_trivial_usage \
        "VTNUM COMMAND [ARGS...]"