Update texts.

doc/help-output.txt

@@ -134,6 +134,8 @@ Global options:
 		w   c   t (File)
 	-[no-]click-to-exit                     Click outside the window to exit
 		True (Default)
+	-[no-]show-match                        Indicate how it match by underlining it.
+		True (Default)
 	-pid [string]                           Pidfile location
 		/tmp/1000-runtime-dir/rofi.pid (File)
 	-kb-primary-paste [string]              Paste primary selection

doc/test_xr.txt

@@ -98,6 +98,8 @@ rofi.fake-background:                screenshot
 rofi.window-format:                  w   c   t
 ! "Click outside the window to exit" Set from: Default
 ! rofi.click-to-exit:                  true
+! "Indicate how it match by underlining it." Set from: Default
+! rofi.show-match:                     true
 ! "Pidfile location" Set from: File
 rofi.pid:                            /tmp/1000-runtime-dir/rofi.pid
 ! "Paste primary selection" Set from: File