README: update few readme notes

Add notes about dfu-util throwing an error and stlink actually working.

BUG=none
TEST=check on gitiles

Change-Id: I496942cad5eef78015a469cc4a1c4c0b7c3b078e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec-aic-tester/+/6174675
Reviewed-by: Keith Short <keithshort@chromium.org>
Tested-by: Fabio Baltieri <fabiobaltieri@google.com>
Commit-Queue: Fabio Baltieri <fabiobaltieri@google.com>

README.md

diff --git a/README.md b/README.md
index 7adb2b2..1af8e83 100644
--- a/README.md
+++ b/README.md
@@ -95,6 +95,9 @@
 west flash -r dfu-util
 ```
 
+NOTE: flashing with dfu-util normally fails in an error and requires a manual
+reset of the board
+
 #### JLink
 
 JLink can be used for both flahing and debugging, requires the [J-Link Software](https://www.segger.com/downloads/jlink/#J-LinkSoftwareAndDocumentationPack) installed.
@@ -122,10 +125,20 @@
 west flash -r stm32cubeprogrammer
 ```
 
+or
+
+```
+west flash -r openocd
+```
+
 or start a debugging session with
 
 ```
 west debug -r stm32cubeprogrammer
 ```
 
-TODO: verify that the ones above actually work and check if openocd works for debugging
+or
+
+```
+west debug -r openocd
+```