update docs for blitz.config.ts

app/pages/docs/blitz-config.mdx

@@ -3,11 +3,8 @@ title: blitz.config.js
 sidebar_label: blitz.config.js
 ---
 
-You can customize advanced behavior of Blitz with `blitz.config.js`.
-
-`blitz.config.js` is a regular Node.js module, not a JSON file. It gets
-used by the Blitz server and build phases, and it's not included in the
-browser build.
+You can customize advanced behavior of Blitz with `blitz.config.js` or
+`blitz.config.ts`.
 
 Take a look at the following `blitz.config.js` example:
 
@@ -33,7 +30,7 @@ can see the available phases
 Phases can be imported from `next/constants`:
 
 ```js
-const {PHASE_DEVELOPMENT_SERVER} = require("next/constants")
+import {PHASE_DEVELOPMENT_SERVER} from "next/constants"
 
 module.exports = (phase, {defaultConfig}) => {
   if (phase === PHASE_DEVELOPMENT_SERVER) {
@@ -57,10 +54,6 @@ understand what each config does, instead, search for the features you
 need to enable or modify in this section and they will show you what to
 do.
 
-> Avoid using new JavaScript features not available in your target Node.js
-> version. `blitz.config.js` will not be parsed by Webpack, Babel or
-> TypeScript.
-
 ## Webpack Config {#webpack-config}
 
 You can customize the Blitz webpack config. See
@@ -93,9 +86,6 @@ module.exports = {
 }
 ```
 
-> Deployments to [Vercel](https://vercel.com) will automatically enable
-> this target. You should not opt-into it yourself.
-
 ## Middleware {#middleware}
 
 HTTP middleware can be added queries and mutations.
@@ -144,8 +134,9 @@ module.exports = {
 
 ### Proxy support {#proxy-support}
 
-Proxy support is enabled automatically for recipe install if either `http_proxy` or `https_proxy`
-environment variable is present. You can also set proxy using:
+Proxy support is enabled automatically for recipe install if either
+`http_proxy` or `https_proxy` environment variable is present. You can
+also set proxy using:
 
 ```js
 module.exports = {
@@ -157,7 +148,8 @@ module.exports = {
 }
 ```
 
-Please note that proxy configuration in `blitz.config.js` will override environment proxy configuration.
+Please note that proxy configuration in `blitz.config.js` will override
+environment proxy configuration.
 
 ## CDN Support with Asset Prefix {#cdn-support-with-asset-prefix}