Add some documentation.

build/openembedded/README

@@ -10,15 +10,20 @@ Instructions for compilation from sources: (requires 10 Go of free space)
 - Choose a distribution and build it.
   For example, to build Angstrom follow the guide at http://www.angstrom-distribution.org/building-angstrom
   For IGEPv2 use environment variable MACHINE=igep0020
+  It is possible to use MACHINE=qemuarm to build an image that can be run on a computer with qemu.
 
 - Add linphone recipes to the pool with an higher priority:
-  Edit conf/bblayers.conf to set EXTRA_LAYERS to point to the source repository of linphone. Search the EXTRALAYERS definition in conf/bblayers.conf
+  Edit conf/bblayers.conf to set EXTRALAYERS to point to the source repository of linphone. Search the EXTRALAYERS definition in conf/bblayers.conf
   and modify it like this:
 
      # Add your overlay location to EXTRALAYERS
      # Make sure to have a conf/layers.conf in there
      EXTRALAYERS ?= "/home/smorlat/sources/git/linphone-daemon/build/openembedded"
 
+  This additional layer gives access to the various linphone recipes but also to a recipe to build an entire image containing linphone.
+  To build this image based on the generic console image you will need to use:
+  bitbake console-linphone-image
+
 
 - Prepare compilation
   Source appropriate environment with "~/.oe/enviro*"  
@@ -28,6 +33,9 @@ Instructions for compilation from sources: (requires 10 Go of free space)
   bitbake -c clean linphone
   bitbake linphone
 
+- If you want additional codecs (e.g. iLBC or AMR) compile linphone-plugins
+  bitbake -c clean linphone-plugins
+  bitbake linphone-plugins
 
 - Find the generated packages "*.ipk"
   Example: /Data/work/angstrom/angstrom-setup-scripts/build/tmp-angstrom_2008_1/deploy/glibc/ipk/armv7a/