data: add BTFS developer docs

[livinglife12]

Add the official BTFS developer documentation to the provider docs field.

Verified source: https://docs.btfs.io/
Grant context: #41

The change was prepared with AI assistance and is submitted for maintainer review; the source link was independently checked before submission. No payout address is included because I do not have the contributor wallet address.

Summary

Type of change

• Add data rows
• Update data rows
• Remove data rows
• Schema change
• Documentation/metadata only

Scope

• Networks affected:

• Categories affected:

• Additional notes, additional context / screenshots:

Links

• Related issue(s)/ DB Improvement Proposal (if schema-related):

Validation checklist

• I followed the Style Guide and Column Definitions. I'm aware of what is !provider syntax, and that entities in /networks sub-folders inherits records from /providers folder
  • Style Guide: https://github.com/Chain-Love/chain-love/wiki/Style-Guide
  • Column Definitions: https://github.com/Chain-Love/chain-love/wiki
• I personally opened and verified every new link I'm adding. I can confirm, that all the links I'm adding are valid.
• If I added new entries - I personally confirmed that the provider I'm adding (modifying) currently supports the adjusted network(s). I've also verified that value in every cell I'm changing is correct according to my best understanding
• This PR is not a blind AI-generated submission

Optional

• Rewards address (for data patching rewards):
• Twitter (X) post link (for +10% of rewards to this PR):

[github-actions]

Summary

Status	Count
🔍 Total	2
🔗 Unique	2
✅ Successful	0
⏳ Timeouts	0
🔀 Redirected	0
👻 Excluded	0
❓ Unknown	0
🚫 Errors	2
⛔ Unsupported	0

Errors per input

Errors in ./references/providers/providers.csv

• [ERROR] https://docs.btfs.io/ (at 2:1) | Connection failed. Check network connectivity and firewall settings
• [ERROR] https://www.btfs.io/ (at 1:1) | Connection failed. Check network connectivity and firewall settings

Full Github Actions output

[USS-Supervisor]

Verdict: REQUEST_CHANGES
Risk: MEDIUM
Summary: The CSV shape is stable, but the reviewer-owned current-cycle link-check reported URL errors for the touched provider row, including the newly added BTFS docs URL.
Findings: references/providers/providers.csv:122 - docs is changed to https://docs.btfs.io/, but current-cycle link-check run 34175221854 reported it as a connection failure. Please replace it with a resolvable official BTFS documentation URL or leave the field empty until the official docs host is reachable.
Confidence: HIGH