ncdu.1: Add new c/C keys

doc/ncdu.pod

@@ -153,6 +153,10 @@ Order by filename (press again for descending order)
 
 Order by filesize (press again for descending order)
 
+=item C
+
+Order by number of items (press again for descending order)
+
 =item a
 
 Toggle between showing disk usage and showing apparent size.
@@ -173,6 +177,10 @@ Toggle between showing percentage, graph, both, or none. Percentage is relative
 to the size of the current directory, graph is relative to the largest item in
 the current directory.
 
+=item c
+
+Toggle display of child item counts.
+
 =item e
 
 Show/hide 'hidden' or 'excluded' files and directories. Please note that even