i.MX RT board flashing and debugging sections are out of date

[MaureenHelm]

Describe the bug
The flashing and debugging sections are out of date for the i.MX RT boards. They incorrectly state the flashing is not supported, and they refer to the generic JLink OpenSDA firmware which cannot program the external flashes on these boards.

To Reproduce
Steps to reproduce the behavior:

1. mkdir build; cd build
2. cmake -DBOARD=mimxrt1060_evk ..
3. make flash or make debug
4. See error

Expected behavior
The application should be programmed into flash.

Impact
Developers not familiar with the board will think there is a bug with the flash programming flow.

Environment (please complete the following information):

• OS: Linux, MacOS, Windows
• Toolchain: Zephyr SDK
• Commit: v1.14.0-rc1

Additional context
N/A