Update documentation for urql (graphql#969)

* Update urql's description and metadata

* Add descriptions as seen for graphql-yoga et al

* Replace "The" with "A"

In our tagline we use "The" on our own pages, and "A" on external
documentation.

Author: kitten

src/content/code/language-support/javascript/client/urql.md

@@ -1,9 +1,15 @@
 ---
 name: urql
-description: A highly customizable and versatile GraphQL client for React.
-url: https://formidable.com/open-source/urql/
+description: A highly customizable and versatile GraphQL client with which you add on features like normalized caching as you grow.
+url: https://formidable.com/open-source/urql/docs/
 github: FormidableLabs/urql
-npm: "urql"
+npm: "@urql/core"
 ---
 
+`urql` is a GraphQL client that exposes a set of helpers for several frameworks.
+It's built to be highly customisable and versatile so you can take it from getting started with your first GraphQL project
+all the way to building complex apps and experimenting with GraphQL clients.
 
+- Currently supports React, React Native, Preact, Svelte, and Vue, and is supported by GraphQL Code Generator.
+- Logical yet simple default behaviour and document caching, and normalized caching via `@urql/exchange-graphcache`
+- Fully customizable behaviour via "exchanges" (addon packages)