docs: link to the C++ bindings

I've added them to the top because I think that alphabetical order makes
sense.
diff --git a/README.md b/README.md
index eb84c38..8f67424 100644
--- a/README.md
+++ b/README.md
@@ -179,6 +179,7 @@
 There are no bindings for other languages directly in this project but they are
 available separately.
 
+* [C++](https://github.com/CESNET/libyang-cpp/)
 * [Rust](https://github.com/rwestphal/yang2-rs/)
 
 ## yanglint