[TUTORIAL] Update repo name in tutos

[LoicPandul]

In various tutorials, especially the contribution tutorials where we discuss using GitHub, there were links or examples that used the old repo name:

DecouvreBitcoin/sovereign-university-data

I have replaced all instances with the correct new name:

PlanB-Network/bitcoin-educational-content

All languages have been updated. No translation needed.

[LoicPandul]

@PaoloFoti

[PaoloFoti]

Thanks man! Just changed title's name