add query and schema specs to description

Author: zkat

src/_includes/partials/description.md

@@ -5,10 +5,15 @@ invoking a bunch of CLI commands! It's meant to be used both as a
 serialization format and a configuration language, much like JSON, YAML, or
 XML.
 
-There's a living
-[specification](https://github.com/kdl-org/kdl/blob/main/SPEC.md), as well as
-various [implementations](#implementations). You can also check out the
-[FAQ](#faq) to answer all your burning questions!
+There's a living [specification](https://github.com/kdl-org/kdl/blob/main/SPEC.md), as well as various
+[implementations](#implementations). You can also check out the [FAQ](#faq) to
+answer all your burning questions!
+
+In addition to a spec for KDL itself, there are also standard specs for [a KDL
+Query Language](https://github.com/kdl-org/kdl/blob/main/QUERY-SPEC.md) based
+on CSS selectors, and [a KDL Schema
+Language](https://github.com/kdl-org/kdl/blob/main/SCHEMA-SPEC.md) loosely
+based on JSON Schema.
 
 The language is based on [SDLang](https://sdlang.org), with a number of
 modifications and clarifications on its syntax and behavior.