Note support for Elixir 1.18

Author: kzemek

README.md

@@ -150,4 +150,4 @@ After `es6_maps` runs as one of the Mix compilers, the Elixir compiler will use
 
 > [!IMPORTANT]
 > By the nature of this solution it's tightly coupled to the internal Elixir implementation.
-> The current version of `es6_maps` should work for Elixir 1.15, 1.16 and the upcoming 1.17 version, but may break in the future.
+> The current version of `es6_maps` should work for Elixir 1.15, 1.16, 1.17 and the upcoming 1.18 version, but may break in the future.