Put spin debug under -vv flag, and add to mosh-client

man/mosh-client.1

@@ -20,6 +20,7 @@ mosh-client \- client-side helper for mosh
 .SH SYNOPSIS
 MOSH_KEY=KEY
 .B mosh-client 
+[\-v]
 IP PORT
 .br
 .B mosh-client 
@@ -49,6 +50,11 @@ directly.
 With the \-c option, \fBmosh-client\fP instead prints the number of colors
 of the terminal given by the TERM environment variable.
 
+The \-v option will print some debugging information on standard
+error.  More instances of this flag will result in more debugging
+information.  If standard error is not redirected from the terminal,
+the display will be corrupted and quickly become unusable.
+
 .SH ENVIRONMENT VARIABLES
 
 .TP