Remove Irys/Bundlr information

[longviewoor]

This PR updates the section in SKILL.md which references Turbo and Irys.

Based on the index.mjs file, from what I can tell it seems like the skill is focused on using Turbo by default.

I also couldn't find any major references to Irys/Bundlr in the minified JS code, other than some mentions of arbundles.

This PR:

• Updates the references to "Turbo (Irys)" / "Turbo/Irys bundling" to instead just use Turbo.
• Removed information on "Turbo requires an Irys node or API key", as user just needs a wallet file to upload from what I understand
• Removed mention of --turbo-node flag as I couldn't find any information on this, and neither could an AI agent.
• Reworks the section to mention that Turbo is used by default

If there's anything incorrect here please let me know and I'm happy to update it where appropriate.

Thanks!