4.6: Add notes on Extended DShot telemetry

[mbuzdalov]

This includes:

• mentioning extended DShot telemetry and that it can send voltage, current etc. via bi-directional DShot;
• extended DShot telemery v2 explanation;
• updating the link to the current Bluejay development repo;
• fixing rpm => RPM where appropriate.

[Hwurzburg]

thanks....most do not write up something for their code and I have to do it....will be merged into wiki when first 4.6 beta is released...I squashed the commits for you