Update HW requirements, node start commands, and node shell scripts

[kpandl]

This PR changes the README.md file and the validator/client/prover shell scripts.

Rendered Version

For the README.md, the PR specifically:

• provides updated HW requirements for validators/clients
• removes official HW recommendations for provers
• introduces the concept of core and outer clients
• updates the recommended start commands of validators/clients

For the corresponding shell scripts, it:

• makes use of the updated start commands
• provides a shell script for core/outer clients instead of general clients
• removes the automatic GitHub update loop (which could trigger a large number of nodes to go offline around the same time)