flashrom.8.tmpl: Add man entry for --extract

This is a follow up change of CB:52450

Signed-off-by: Daniel Campello <campello@chromium.org>
Change-Id: Icc068f5545b6f30ac390b7b815a31e2d61bf4789
Reviewed-on: https://review.coreboot.org/c/flashrom/+/52892
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
diff --git a/flashrom.8.tmpl b/flashrom.8.tmpl
index 4634539..4ae7e71 100644
--- a/flashrom.8.tmpl
+++ b/flashrom.8.tmpl
@@ -47,7 +47,7 @@
 .B flashrom \fR[\fB\-h\fR|\fB\-R\fR|\fB\-L\fR|\fB\-z\fR|
           \fB\-p\fR <programmername>[:<parameters>] [\fB\-c\fR <chipname>]
             (\fB\-\-flash\-name\fR|\fB\-\-flash\-size\fR|
-             [\fB\-E\fR|\fB\-r\fR <file>|\fB\-w\fR <file>|\fB\-v\fR <file>]
+             [\fB\-E\fR|\fB\-x\fR|\fB\-r\fR <file>|\fB\-w\fR <file>|\fB\-v\fR <file>]
              [(\fB\-l\fR <file>|\fB\-\-ifd|\fB \-\-fmap\fR|\fB\-\-fmap-file\fR <file>)
                [\fB\-i\fR <image>[:<file>]]]
              [\fB\-n\fR] [\fB\-N\fR] [\fB\-f\fR])]
@@ -136,6 +136,10 @@
 .B "\-E, \-\-erase"
 Erase the flash ROM chip.
 .TP
+.B "\-x, \-\-extract"
+Extract every region defined on the layout from flash ROM chip to a
+file with the same name as the extracted region.
+.TP
 .B "\-V, \-\-verbose"
 More verbose output. This option can be supplied multiple times
 (max. 3 times, i.e.