cleanup some uncessary tasks; add helpful info

[mycodecrafting]

Description

• Remove unnecessary dev-cluster cloning step from Digital Ocean guide
• Add a step to the astria-cli installation to move the binary into the shell path
• Add a note for required cluster node sizing (for celestia pod)
• Add a note for rollup name length limitations
  • K8s label names are limited to 63 chars. One of the labels concats the rollup name with -celestia-node-light-mocha-4-token-service effectively limiting the current max length of a rollup name to 21 chars.

Motivation and Context

This will help users follow the guide while avoiding pitfalls and errors

Types of changes

• Edits to existing documentation
• Changing documentation structure (relocating existing files, ensure redirects exist)
• Stylistic changes (provide screenshots above)