Update build producer document for AGL IC container integration

Update build producer document for AGL IC container integration

Updating AGL IC container integration documentation based on revised
documentation available on confluence
https://confluence.automotivelinux.org/display/IC/Build+Procedure+for+AGL+IC+with+Container+Integration

Bug-AGL: [SPEC-4805]
Signed-off-by: Vinod Ahuja <vahuja@unomaha.edu>
Change-Id: I6f49d3ee846bfee371662d0ac1b98dbd3fd76bbb
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/documentation/+/29000
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>
Tested-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>
(cherry picked from commit c71f2899ee9c53f69d64ff44aeebf5f36eb0ac0b)
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/documentation/+/29077