Bug#577461: installation-guide: Updates to textmode activation

[Samuel Thibault <sthibault@debian.org>]

Ah, sorry, I thought that what follows would have been independent from
this bugreport but actually it's not.

The help menu is in textmode and can be used to type boot parameters
etc., so let's document that too.

Samuel

Index: en/boot-installer/accessibility.xml
===================================================================
--- en/boot-installer/accessibility.xml	(révision 62894)
+++ en/boot-installer/accessibility.xml	(copie de travail)
@@ -81,13 +81,24 @@
 </para>
   </sect2>
 
-  <sect2><title>Board Devices</title>
+  <sect2><title>Board Devices and virtualization</title>
 <para>
 
 Some accessibility devices are actual boards that are plugged inside the
-machine and that read text directly from the video memory. To get them
-to work framebuffer support must be disabled by using the
-<userinput>fb=false</userinput> boot parameter. This will however reduce
+machine and that read text directly from the video memory. Also, some
+virtualization tools have a textual interface (e.g. <userinput>qemu
+-curses</userinput>).
+
+</para><para>
+
+For such case, a textual version of the bootloader can be activated by typing
+<userinput>h</userinput> &enterkey; . This permits to easily append boot
+parameters at will.
+
+</para><para>
+
+The purely textual version of the installer must also be activated by using the
+<userinput>vga=0 fb=false</userinput> boot parameter. This will however reduce
 the number of available languages.
 
 </para>