patch 8.2.4088: xxd cannot output everything in one line

Problem:    Xxd cannot output everything in one line.
Solution:   Make zero columns mean infinite columns. (Erik Auerswald,
            closes #9524)
diff --git a/runtime/doc/xxd.1 b/runtime/doc/xxd.1
index 46bfedc..fb0ac44 100644
--- a/runtime/doc/xxd.1
+++ b/runtime/doc/xxd.1
@@ -70,6 +70,7 @@
 Format
 .RI < cols >
 octets per line. Default 16 (\-i: 12, \-ps: 30, \-b: 6). Max 256.
+No maxmimum for \-ps. With \-ps, 0 results in one long line of output.
 .TP
 .IR \-C " | " \-capitalize
 Capitalize variable names in C include file style, when using \-i.