ps: Add IO Accounting fields

Add the fields for the IO accounting to ps as the library now
has them added from previous commit.

References:
 commit a7afe06e6f

ps/ps.1

@@ -1524,6 +1524,14 @@ psr	PSR	T{
 processor that process last executed on.
 T}
 
+rbytes	RBYTES	T{
+Number of bytes which this process really did cause to be fetched from the storage layer.
+T}
+
+rchars	RCHARS	T{
+Number of bytes which this task has caused to be read from storage.
+T}
+
 rgid	RGID	T{
 real group ID.
 T}
@@ -1533,6 +1541,11 @@ real group name.  This will be the textual group ID, if it can be obtained
 and the field width permits, or a decimal representation otherwise.
 T}
 
+rops	ROPS	T{
+Number of read I/O operations—that is, system calls such as
+.BR read "(2) and " pread (2).
+T}
+
 rss	RSS	T{
 resident set size, the non\-swapped physical memory that a task has used (in
 kiloBytes).  (alias
@@ -1866,10 +1879,27 @@ mappings are currently excluded; this is subject to change.  (alias
 .BR vsize ).
 T}
 
+wbytes	WBYTES	T{
+Number of bytes which this process caused to be sent to the storage layer.
+T}
+
+wcbytes	WCBYTES	T{
+Number of cancelled write bytes.
+T}
+
 wchan	WCHAN	T{
 name of the kernel function in which the process is sleeping.
 T}
 
+wchars	WCHARS	T{
+Number of bytes which this task has caused, or shall cause to be written to disk.
+T}
+
+wops	WOPS	T{
+Number of write I/O operations—that is, system calls such as
+.BR write "(2) and " pwrite (2).
+T}
+
 .TE
 .\" #######################################################################
 .PP