Mention sort -h.

Fixes #26.

README.md

@@ -194,9 +194,7 @@ Notes:
 
 - Use `shuf` to shuffle or select random lines from a file.
 
-- Know `sort`'s options. Know how keys work (`-t` and `-k`). In particular, watch out that you need to write `-k1,1` to sort by only the first field; `-k1` means sort according to the whole line.
-
-- Stable sort (`sort -s`) can be useful. For example, to sort first by field 2, then secondarily by field 1, you can use `sort -k1,1 | sort -s -k2,2`
+- Know `sort`'s options. Know how keys work (`-t` and `-k`). In particular, watch out that you need to write `-k1,1` to sort by only the first field; `-k1` means sort according to the whole line. Stable sort (`sort -s`) can be useful. For example, to sort first by field 2, then secondarily by field 1, you can use `sort -k1,1 | sort -s -k2,2`. For handling human-readable numbers (e.g. from `du -h`) use `sort -h`.
 
 - If you ever need to write a tab literal in a command line in Bash (e.g. for the -t argument to sort), press **ctrl-v** **[Tab]** or write `$'\t'` (the latter is better as you can copy/paste it).