Improve README

Author: mthh

README.md

@@ -2,11 +2,14 @@
 
 [![Build](https://github.com/mthh/sfcgal-sys/actions/workflows/test.yml/badge.svg)](https://github.com/mthh/sfcgal-sys/actions/workflows/test.yml)
 [![Crates.io](https://img.shields.io/crates/v/sfcgal-sys.svg)](https://crates.io/crates/sfcgal-sys)
+[![Static Badge](https://img.shields.io/badge/documentation-0.7-green)](https://mthh.github.io/sfcgal-sys/sfcgal_sys/)
 
 Rust low-level FFI bindings to [`SFCGAL`](https://sfcgal.gitlab.io/SFCGAL/) 1.5.x C API.  
 Don't use this crate directly, prefer it's higher-level wrapper : [sfcgal-rs](https://github.com/mthh/sfcgal-rs).
 
-[Documentation](https://mthh.github.io/sfcgal-rs/sfcgal_sys/)
+> [!IMPORTANT]
+> Note that the required version of SFCGAL is currently 1.5.x (latest version - 2023-10-30).  
+> If you want to use SFCCAL 1.4.x, you can use the 0.6.x version of this crate / of [sfcgal-rs](https://github.com/mthh/sfcgal-rs).
 
 ## Internals