docs: add SF_README.md (short, beginner-friendly guide) — fix #135

Adds a Straightforward README that's short, plain-language, and skips
the technical "how it works" diagrams. Covers the same setup flow as
the main README but with friendlier wording, plus a "Common issues"
section that surfaces the most-asked-about gotchas (YouTube SafeSearch
loop #61, Cloudflare Turnstile loop, 504 Relay timeout, daily quota,
"connected but nothing loads"). Both English and Persian.

The main README's index line now offers four links instead of two:
  - Quick Start (EN)
  - Full English README
  - راهنمای خلاصه فارسی
  - راهنمای کامل فارسی

So users who don't have a deep networking background can land on a
guide tailored to them, and users who want the full picture still
have a single click.

Closes #135.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

README.md

@@ -13,7 +13,9 @@ Free DPI bypass via Google Apps Script as a remote relay, with TLS SNI concealme
 
 > **Heads up on authorship:** the bulk of this Rust port was written with [Anthropic's Claude](https://claude.com) driving, reviewed by a human on every commit. Bug reports, fixes, and contributions are all welcome — see the [issues page](https://github.com/therealaleph/MasterHttpRelayVPN-RUST/issues).
 
-**[English Guide](#setup-guide)** | **[راهنمای فارسی](#راهنمای-فارسی)**
+**[Quick Start (English)](SF_README.md#quick-start)** | **[راهنمای کامل English](#setup-guide)** | **[راهنمای خلاصه فارسی](SF_README.md#راهنمای-خلاصه-فارسی)** | **[راهنمای کامل فارسی](#راهنمای-فارسی)**
+
+> **New here?** The Quick Start versions are short, plain-language, and cover the most common questions. The full guides have everything else (config options, full tunnel mode, OpenWRT, security notes).
 
 ## Why this exists