[PATCH v5 11/16] binman: Add a separate section about environment variables

[Simon Glass]

These are documented in various several sections. Add a new section that
mentions them all in one place so it is easier to see what environment
variables can be used to control U-Boot's use of binman.

Signed-off-by: Simon Glass <sjg at chromium.org>
Suggested-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
---

Changes in v5:
- Add new patch with a separate section about environment variables

 tools/binman/binman.rst | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

Applied to u-boot-dm, thanks!