Document MSYS2 MINGW64 environment support (#806)

Co-authored-by: Johannes Müller <[email protected]>

docs/man/required_libraries.md

@@ -5,7 +5,7 @@ This is a list of third-party libraries used by the Crystal compiler and the sta
 ## Core runtime dependencies
 
 The libraries in this section are always required by Crystal's stdlib runtime. They must be present for building or running any Crystal program that uses the standard library.
-Avoiding these dependencies is only possible when not using the standard library (`--prelude=none` compiler option).
+Avoiding these dependencies is only possible when not using the standard library (`--prelude=empty` compiler option).
 
 ### System library
 
@@ -22,7 +22,8 @@ which may be part of the C library or standalone libraries. On most platforms al
 | [OpenBSD libc][openbsd-libc] | standard C library for OpenBSD <br>**Supported versions:** 6+ | [BSD](https://www.openbsd.org/policy.html) |
 | [Dragonfly libc][dragonfly-libc] | standard C library for DragonflyBSD | [BSD](https://www.dragonflybsd.org/docs/developer/DragonFly_BSD_License/) |
 | [macOS libsystem][macos-libsystem] | standard C library for macOS <br>**Supported versions:** 11+ | [Apple](https://github.com/apple-oss-distributions/Libsystem/blob/main/APPLE_LICENSE) |
-| [MSVCRT][msvcrt] | standard C library for MSVC compiler (Windows) | |
+| [MSVCRT][msvcrt] | standard C library for Visual Studio 2013 or below | |
+| [UCRT][ucrt] | Universal CRT for Windows / Visual Studio 2015+ | [MIT subset available](https://www.nuget.org/packages/Microsoft.Windows.SDK.CRTSource/10.0.22621.3/License) |
 | [WASI][wasi] | WebAssembly System Interface | [Apache v2 and others](https://github.com/WebAssembly/wasi-libc/blob/main/LICENSE) |
 | [bionic libc][bionic-libc] | C library for Android <br>**Supported versions:** ABI Level 24+ | [BSD-like](https://android.googlesource.com/platform/bionic/+/refs/heads/master/libc/NOTICE) |
 
@@ -113,10 +114,11 @@ In addition to the [core runtime dependencies](#core-runtime-dependencies), thes
 [libxml2]: http://xmlsoft.org/
 [libyaml]: https://pyyaml.org/wiki/LibYAML
 [macos-libsystem]: https://github.com/apple-oss-distributions/Libsystem
-[msvcrt]: https://learn.microsoft.com/en-us/cpp/c-runtime-library/crt-library-features?view=msvc-170
+[msvcrt]: https://web.archive.org/web/20150630135610/https://msdn.microsoft.com/en-us/library/abx4dbyh.aspx
 [musl-libc]: https://musl.libc.org/
 [netbsd-libc]: http://cvsweb.netbsd.org/bsdweb.cgi/src/lib/libc/?only_with_tag=MAIN
 [openbsd-libc]: http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/lib/libc/
 [openssl]: https://www.openssl.org/
+[ucrt]: https://learn.microsoft.com/en-us/cpp/windows/universal-crt-deployment?view=msvc-170
 [wasi]: https://wasi.dev/
 [zlib]: http://zlib.net/

docs/syntax_and_semantics/platform_support.md

@@ -55,7 +55,7 @@ Most typically, some parts of the standard library are not supported completely.
 | Target | Description | Supported versions | Comment |
 | ------ | ----------- | ------------------ | ------- |
 | `x86_64-windows-msvc` | x64 Windows (MSVC) | 7+ | :material-circle-slice-7: tests<br> :material-checkbox-marked-circle: builds |
-| `x86_64-windows-gnu` | x64 Windows (MinGW-w64) | 7+, MSYS2 `UCRT64` or `CLANG64` environment | :material-circle-slice-7: tests<br> :material-checkbox-marked-circle: builds |
+| `x86_64-windows-gnu` | x64 Windows (MinGW-w64) | 7+, MSYS2 `UCRT64` / `MINGW64` / `CLANG64` environment | :material-circle-slice-7: tests<br> :material-checkbox-marked-circle: builds |
 | `aarch64-windows-msvc` | ARM64 Windows (MSVC) | 11+ | :material-selection-ellipse: tests<br> :material-selection-ellipse: builds |
 | `aarch64-windows-gnu` | ARM64 Windows (MinGW-w64) | 11+, MSYS2 `CLANGARM64` environment | :material-selection-ellipse: tests<br> :material-selection-ellipse: builds |
 | `aarch64-linux-android` | aarch64 Android  | Bionic C runtime, API level 24+ | :material-selection-ellipse: tests<br> :material-selection-ellipse: builds |