rename repo and website URL: `tutorials-primer`

[avallecam]

alternatives:

• tutorials-intro (reference: https://www.openintro.org/)
• tutorials-starter
• tutorials-foundation
• tutorials-primer (reference: https://r-primers.andrewheiss.com/) +1 by claude

Then add it under the tutorial English https://epiverse-trace.github.io/learn

Also, link to this on prerequisites in episodes of early, middle, late.

as discussed with @Degoot-AM