Update: update readme.md

[vcaesar]

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Description

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[Copilot]

Pull request overview

This PR updates the Windows installation instructions in the README.md file to improve clarity and provide more installation options for MinGW/GCC compilers. The changes reorganize the installation instructions by separating different MinGW variants and adding a new winget installation option for WinLibs.

• Restructured MinGW installation section to highlight llvm-mingw and MinGW-w64 separately
• Added winget installation command for WinLibs POSIX UCRT variant
• Clarified environment variable setup instructions with more detailed guidance

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[Copilot]

Spelling error: "Mingw-w64" should be consistently capitalized. The original text used "MinGW-w64" (capital G), but this change introduces "Mingw-w64" (lowercase g). For consistency with the official project name and other references in the document, it should be "MinGW-w64".

Suggested change

	or [Mingw-w64](https://sourceforge.net/projects/mingw-w64/files)
	or [MinGW-w64](https://sourceforge.net/projects/mingw-w64/files)

[Copilot]

Spelling error: "Mingw-w64" should be consistently capitalized. The original text used "MinGW-w64" (capital G), but this change introduces "Mingw-w64" (lowercase g). For consistency with the official project name and other references in the document, it should be "MinGW-w64".

Suggested change

	Or Download the [Mingw-w64](https://sourceforge.net/projects/mingw-w64/files) and the others gcc, then set system environment variables like `C:\mingw64\bin` to the env `Path`.
	Or Download the [MinGW-w64](https://sourceforge.net/projects/mingw-w64/files) and the others gcc, then set system environment variables like `C:\mingw64\bin` to the env `Path`.

[Copilot]

Grammatical error: "Or The others GCC" is grammatically incorrect. It should be either "Or other GCC implementations" or "Or the other GCC compilers" for proper English grammar.

Suggested change

	`Or The others GCC` (Except the Mingw-w64, you should compile the "libpng" with yourself when use the [bitmap](https://github.com/vcaesar/bitmap).)
	`Or other GCC implementations` (Except for Mingw-w64, you should compile "libpng" yourself when using the [bitmap](https://github.com/vcaesar/bitmap).)

[Copilot]

Grammatical error: "and the others gcc" is grammatically incorrect. It should be either "and other gcc compilers" or "and the other gcc implementations" for proper English grammar.

Suggested change

	Or Download the [Mingw-w64](https://sourceforge.net/projects/mingw-w64/files) and the others gcc, then set system environment variables like `C:\mingw64\bin` to the env `Path`.
	Or download the [Mingw-w64](https://sourceforge.net/projects/mingw-w64/files) and other GCC compilers, then set system environment variables like `C:\mingw64\bin` to the env `Path`.