[PATCH v2 21/28] buildman: Update the 'theory of operation' a little

[sjg at google.com]

Make a few updates to this important section of the documentation, to
make things clearer.

Signed-off-by: Simon Glass <sjg at chromium.org>
---

Changes in v2: None

 tools/buildman/README | 69 ++++++++++++++++++++++++-------------------
 1 file changed, 39 insertions(+), 30 deletions(-)

Applied to u-boot-dm, thanks!