Add Silicon Labs EFR32/EZSP flashing info and links

[Hedda]

Add some basic information and links regarding how to flash Silabs EZSP based Zigbee adapters like EFR32.

@kirovilya @MattWestb @Loic691 can you have feedback/input on this EFR32/EZSP flashing info and links?

[Loic691]

what kind of information do you want ?

[Hedda]

what kind of information do you want ?

For example method did you flash your Sonoff ZBDongle-E with?

[Hedda]

Originally posted by @Koenkk in Koenkk/zigbee2mqtt#13894 (comment)

Great, can you also make a pr for the docs with the link to the fw? Adding it to the description makes it too long.

@sujithg9 maybe can this flasing info maybe also be reused for docs Sonoff ZBDongle-E/Dongle-E with Zigbee Router firmware?

Koenkk/zigbee2mqtt#13894

Koenkk/zigbee-herdsman-converters#4641

[github-actions]

This pull request is stale because it has been open 30 days with no activity. Remove stale label or comment or this will be closed in 7 days

[Hedda]

Not stale.

[Hedda]

Added URL link to the new "Universal Silicon Labs Flasher" by puddly

https://github.com/puddly/universal-silabs-flasher

FYI, that will soon ship with Home Assistant as part on their official silabs-multiprotocol addon (based on agners silabs flasher)

[Koenkk]

Thanks!