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

README

@@ -82,6 +82,9 @@ Downloading the current source code:
   is generally a faster way of getting it fixed, and the complete archive of
   what happened is the subversion changelog.
 
+  Note: if you want to compile busybox in a busybox environment you must
+  select ENABLE_DESKTOP.
+
 ----------------
 
 getting help: