Add description of Xcode and Windows to install file, Fixes #10281

Changes

@@ -143,6 +143,9 @@ Working version
   (Nicolás Ojeda Bär, report by Daniel Bünzli, review by David Allsopp,
   Sébastien Hinderer, and Daniel Bünzli)
 
+- #10281: Add description of C compiler on macOS and Windows platforms.
+  (Dong An)
+
 ### Compiler user-interface and warnings:
 
 - #10328: Give more precise error when disambiguation could not possibly work.

INSTALL.adoc

@@ -3,10 +3,20 @@
 == Prerequisites
 
 * A C Compiler is required.
-  The GNU C Compiler (`gcc`) is recommended as the bytecode interpreter takes
+  ** For GNU/Linux +
+    The GNU C Compiler (`gcc`) is recommended as the bytecode interpreter takes
   advantage of GCC-specific features to enhance performance. gcc is the standard
   compiler under Linux and many other systems.
-  However `clang` - used in Mac OS, BSDs and others - also works fine.
+
+  ** For BSDs +
+    `Clang` is the default C compiler under BSDs - also works fine.
+
+  ** For MacOS +
+    `Clang` is the default C compiler under MacOS. If MacOS complains no C compiler was installed while OCaml installing,
+    please run command `xcode-select --install` to install command-line tools and required libraries and header files.
+
+  ** For Windows +
+    Install https://docs.microsoft.com/en-us/windows/wsl/compare-versions[WSL2] or http://www.cygwin.com/[Cygwin].
 
 * GNU `make`, as well as POSIX-compatible `awk` and `sed` are required.