[BUG] intro to skills should point at github repo as install prereq

### Affected Notebook/File

skills-notebooks-01-skills-introduction

### Bug Description

Re: https://platform.claude.com/cookbook/skills-notebooks-01-skills-introduction

When following docs to learn about skills, the very first instruction is "cd /path/to/claude-cookbooks/skills" but it doesn't ever say where you're supposed to find that directory. Turns out it's a github repo, which you're supposed to clone first. That would be helpful to mention in the "prerequisites" section.

### Steps to Reproduce

1. go to https://platform.claude.com/cookbook/skills-notebooks-01-skills-introduction
2. try to follow the instructions without first having cloned a github repo which is never mentioned
3. be frustrated

### Error Message

```shell

```

### Environment

this environment-independent

### Would you be willing to submit a PR to fix this?

No, I'm just reporting