doc: update sigrok-cli(1) for channel assignment to decoder inputs

Extend the sigrok-cli manpage section which discusses the -P option.
Mention the assignment of logic channels to decoder inputs by index
or by name.

Automatic assignment by position in the absence of user specs seems
to not have been recent implementations' default behaviour. Remove
that outdated or incorrect comment.

doc/sigrok-cli.1

@@ -1,4 +1,4 @@
-.TH SIGROK\-CLI 1 "March 28, 2019"
+.TH SIGROK\-CLI 1 "April 07, 2023"
 .SH "NAME"
 sigrok\-cli \- Command-line client for the sigrok software
 .SH "SYNOPSIS"
@@ -311,15 +311,27 @@ In this example,
 .B wordsize
 is an option supported by the
 .B spi
-protocol decoder. Additionally, the user tells sigrok to decode the SPI
+protocol decoder. Additionally, the user requests sigrok to decode the SPI
 protocol using channel 1 as MISO signal for SPI, channel 5 as MOSI, channel 3
 as CLK, and channel 0 as CS# signal.
 .sp
-Notice that the
+The
 .B sigrok\-cli
-application does not support "name matching". Instead it's assumed that the
-traces in the input stream match the order of the decoder's input signals,
-or that users explicitly specify the input channel to decoder signal mapping.
+application can automatically assign logic channels to decoder inputs
+in their strict channel index order (by means of the
+.B auto_index
+keyword), or can automatically assign logic channels to decoder inputs
+when their names match (case insensitive match,
+.B auto_names
+keyword). Users need to explicitly request this assignment, the default
+behaviour is to not automatically assign any signals.
+.sp
+Example:
+.sp
+ $
+.B "sigrok\-cli \-i <file.sr>"
+.br
+.B "              \-P ieee488:assign_channels=auto_names"
 .br
 .sp
 When multiple decoders are specified in the same