updated introduction to Zephyr RTOS page

See merge request docs/docs.beagleboard.io!170

Authored by: Deepak Khatri

Enhance - Simplified and clarified setup of tools, extended inclusion of SMARTHLS tools

See merge request !168

beaglev-fire: specify baud rate to access terminal

See merge request !169

The command to access the terminal using tio did not specify the baud rate
115200, therefore specify it to establish reliable serial communication.

Signed-off-by: Prajna Rajendra Kumar <prajna.rajendrakumar@microchip.com>

beaglev-fire: include steps to flash image using dd

See merge request !167

Merge branch 'main' of https://git.beagleboard.org/docs/docs.beagleboard.io into prajnark_update_flashing

BeaglePlay: add nodered guide

See merge request !96

Remove a non existent reference and fix build error

Signed-off-by: Dhruva Gole <d-gole@ti.com>

Also reword the pre requisites to use :ref:

Signed-off-by: Dhruva Gole <d-gole@ti.com>

Also add a link and capitalise Accel click.
Minor fixes and add note in pre req

Signed-off-by: Dhruva Gole <d-gole@ti.com>