docs: add wRTC Quickstart guide (#58)

[zhanglinqian]

This PR adds a comprehensive wRTC Quickstart guide as requested in issue #58.

Changes

• Create with complete guide
• Add anti-scam checklist (verify mint, decimals, DEX, bridge)
• Include copy-pastable steps for:
  • Swapping on Raydium
  • Bridging to BoTTube credits
  • Using credits for tipping
  • Security best practices
  • Troubleshooting
• Link from main README to wRTC guide

Documentation Content

The guide includes:

• wRTC Overview: Mint, decimals, links to DEX and bridge
• Anti-Scam Checklist: 5 critical verification steps
• Step-by-Step Guide:
  1. Buying/obtaining wRTC on Raydium
  2. Verifying balance
  3. Bridging to BoTTube credits
  4. Using credits for tipping
  5. (Optional) Withdrawing back to RustChain
• Price & Market Data: Links to Raydium, DexScreener
• Security Best Practices: Wallet security, transaction safety
• Troubleshooting: Common problems and solutions
• Support Links: Discord, Twitter, GitHub issues

Acceptance Criteria

• PR merged
• Doc is readable and does not require insider knowledge
• Linked from main README
• All code snippets are copy-pastable

Fixes #58

[Scottcjn]

Thanks for the submission. Closing this as duplicate/noise for payout triage.

Why: this overlaps existing wRTC onboarding work already under review, and several quickstart PRs reference bounty #58 which is now a red-team consensus bounty (not docs).

How to get paid next round:

1. Submit a focused follow-up diff that adds missing proof/screenshots to the accepted onboarding doc path
2. Or pick another active bounty with distinct scope: feat: Add BoTTube <-> RustChain Bridge Daemon #99 (challenge), feat: Add Windows Installer for RustChain Miner #100 (discovery), fix(security): harden /wallet/transfer/signed validation & error handling #103 (X + BoTTube), #124 (profile avatar+bio), [BOUNTY] Security Red Team - Vulnerability Scanner (#57) #72 docs items not yet covered
3. Include claim format + RTC wallet + verification evidence in the bounty issue

Keep participating. Quality submissions that meet scope and proof requirements are paid.