Fabric: exact instance configuration details in cluster creation documentation

### Issue Type

Incorrect information

### Content Location

https://github.com/HarperFast/documentation/blob/main/fabric/cluster-creation-management.md

### What's wrong?

This page:

https://github.com/HarperFast/documentation/blob/main/fabric/cluster-creation-management.md

Should define exact performance metrics for "Free, Medium, High, Very High". - or provide a link to this information.

I believe them to be...

- Free: 5 GB storage, 1 core, 2 threads, 1 GB memory
- Medium: 10 GB storage, 1 core, 2 threads, 2 GB memory
- High: 20 GB storage, 4 cores, 8 threads, 4 GB memory

But I'm not entirely certain.

### Suggested improvement

_No response_

### Additional context

_No response_

### Are you planning to fix this issue?

No, just reporting the issue

### First-time contributor support

- [ ] I'm new to contributing and would appreciate guidance on the process
- [ ] I'd like help understanding the project structure
- [ ] I need assistance with setting up the development environment
- [ ] I'm comfortable contributing but new to this project specifically