Update requirements to include Fil-C support

Added support for Fil-C, the memory-safe C/C++ compiler.

Author: lemire

README.md

@@ -89,7 +89,7 @@ of the latest hardware. Roaring bitmaps are already available on a variety of pl
 
 - Linux, macOS, FreeBSD, Windows (MSYS2 and Microsoft Visual studio).
 - We test the library with ARM, x64/x86 and POWER processors. We only support little endian systems (big endian systems are vanishingly rare).
-- Recent C compiler supporting the C11 standard (GCC 7 or better, LLVM 8 or better (clang), Xcode 11 or better, Microsoft Visual Studio 2022 or better, Intel oneAPI Compiler 2023.2 or better), there is also an optional C++ class that requires a C++ compiler supporting the C++11 standard.
+- Recent C compiler supporting the C11 standard (GCC 7 or better, LLVM 8 or better (clang), Xcode 11 or better, Microsoft Visual Studio 2022 or better, Intel oneAPI Compiler 2023.2 or better), there is also an optional C++ class that requires a C++ compiler supporting the C++11 standard. We support [Fil-C, the memory-safe C/C++ compiler](https://fil-c.org).
 - CMake (to contribute to the project, users can rely on amalgamation/unity builds if they do not wish to use CMake).
 - The CMake system assumes that git is available.
 - Under x64 systems, the library provides runtime dispatch so that optimized functions are called based on the detected CPU features. It works with GCC, clang (version 9 and up) and Visual Studio (2017 and up). Other systems (e.g., ARM) do not need runtime dispatch.