Added an overview of EL 6.0 to the introduction

spec/src/main/asciidoc/ELSpec.adoc

diff --git a/spec/src/main/asciidoc/ELSpec.adoc b/spec/src/main/asciidoc/ELSpec.adoc
index 34ddad3..591ddde 100644
--- a/spec/src/main/asciidoc/ELSpec.adoc
+++ b/spec/src/main/asciidoc/ELSpec.adoc
@@ -137,6 +137,11 @@
 and use of FeatureDescriptor was deprecated with a view to removing the
 dependency on the `java.desktop` module.
 
+EL 6.0 made Java 17 the minimum version, removed deprecated code and made the
+dependency on the `java.desktop` module optional. New resolvers have been added
+for `java.lang.Record` and `java.lang.Optional` instances and support for the
+`length` property has been added to arrays.
+
 ==== EL in a nutshell
 
 The syntax is quite simple. Model objects are