Add documentation for new multiarch features

Change-Id: I7cdfc06e095cfacec72fea2ad118f1b762e44591
Blueprint: multiarch-support
Depends-On: I7c84f3035853d8ee7b8d45895e7acce8e9dd3d13

doc/source/install/basic_deployment/basic_deployment_cli.rst

@@ -272,6 +272,23 @@ Load the images into the containerized undercloud Glance::
 
 To upload a single image, see :doc:`../post_deployment/upload_single_image`.
 
+If working with multiple atchitectures and/or plaforms with an architecure these
+attributes can be specified at upload time as in::
+
+    openstack overcloud image upload
+    openstack overcloud image upload --arch x86_64 \
+        --httpboot /httpboot/x86_64
+    openstack overcloud image upload --arch x86_64 --platform SNB \
+        --httpboot /httpboot/x86_64-SNB
+
+.. note::
+
+    Adding --httpboot is optional but suggested if you need to ensure that the
+    ``agent`` images are unique within your environment.
+
+This will create 3 sets of images with in the undercloud image service for later
+use in deployment, see :doc:`../environments/baremetal`
+
 Register Nodes
 --------------
 

doc/source/install/environments/baremetal.rst

@@ -228,6 +228,12 @@ user identifying machines inside ``instackenv.json`` file:
   description and so on). Note that this field will not be considered by
   Ironic during the import
 
+Also if you're working in a diverse environment with multiple architectures
+and/or platforms within an architecture you may find it necessary to include a
+platform field:
+
+* ``platform`` - String paired with images to fine tune image selection
+
 For example::
 
   {