Update "Hello plu-ts" example project on documentation

[EehMauro]

Update the current "Hello plu-ts" example on the docs

Acceptance criteria

• [x] Update the instructions on the documentation repo
• [x] Update the hello-pluts-react repo (Replacing Koios dependency with Blockfrost)
• [x] Update the hello-pluts-react-final repo (Replacing Koios dependency with Blockfrost)