docs: clarify README device support and remove outdated compatibility claim

[NathanNeurotic]

Motivation

• Remove an outdated, unqualified claim that OPL is “the most compatible homebrew loader” to avoid misleading users.
• Explicitly represent MMCE as its own supported device/protocol and ensure internal HDD exFAT support is clearly documented.
• Align the TOC, section headings, and Quick Start wording with current feature coverage so users can find guidance reliably.

Description

• Updated the README TOC entry and section header to USB/MMCE/MX4SIO/iLink for consistent naming and linking.
• Replaced the five-item device list with a six-item list that adds MMCE (Memory Card Mass Storage protocol devices) and clarifies internal HDD exFAT (MBR/GPT) support.
• Removed the sentence claiming OPL is “the most compatible homebrew loader.”
• Split the combined MMCE/MX4SIO bullet into separate bullets and updated Quick Start wording to include MMCE, MX4SIO, and exFAT where applicable.

Testing

• Verified the README contents with sed -n '1,260p' README.md to inspect the file and confirm edits succeeded.
• Searched the updated text with rg -n "USB/MX4SIO|MMCE-compatible|most compatible|USB/MMCE" README.md to confirm removal/addition of targeted phrases.
• Displayed a focused portion of the file with nl -ba README.md | sed -n '10,170p' to validate the TOC, device list, and feature bullets render as intended; all checks succeeded.

---

Codex Task

[gemini-code-assist]

Warning

You have reached your daily quota limit. Please wait up to 24 hours and I will start processing your requests again!