ARCHITECTURE: Update code map
ARCHITECTURE: Update code map

Add explanation on several components I'm a bit familiar with.

BUG=b:195003973
TEST=none

Change-Id: I7c4c6ebc266ae40dadfb984e9dff8016efe6ab73
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3188676
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Commit-Queue: Keiichi Watanabe <815e4e8f7c92a23424d7c3f51ead622bcedbc720@chromium.org>
Reviewed-by: Chirantan Ekbote <35787c0e27de5c48735e07f8324823b765e8bcbc@chromium.org>
Reviewed-by: Dennis Kempin <cd09796fb571bec2782819dbfd33307f65b1c778@google.com>

google/crosvm,google/crosvm,google/crosvm,google/crosvm