Remove outdated documentation (#20714)

Fixes #20487

docs/api-reference/next.config.js/build-target.md

----
-description: Learn more about the build targets used by Next.js, which decide the way your application is built and run.
----
-
-# Build Target
-
-Next.js supports various build targets, each changing the way your application is built and run. We'll explain each of the targets below.
-
-## `server` target
-
-> This is the default target, however, we highly recommend the [`serverless` target](#serverless-target). The `serverless` target enforces [additional constraints](https://rauchg.com/2020/2019-in-review#serverless-upgrades-itself) to keep you in the [Pit of Success](https://blog.codinghorror.com/falling-into-the-pit-of-success/).
-
-This target is compatible with both `next start` and [custom server](/docs/advanced-features/custom-server.md) setups (it's mandatory for a custom server).
-
-Your application will be built and deployed as a monolith. This is the default target and no action is required on your part to opt-in.
-
-## `serverless` target
-
-> Deployments to [Vercel](https://vercel.com) will automatically enable this target. You should not opt-into it yourself.
-
-This target will output independent pages that don't require a monolithic server.
-
-It's only compatible with `next start` or Serverless deployment platforms (like [Vercel](https://vercel.com)) — you cannot use the custom server API.
-
-To opt-into this target, set the following configuration in your `next.config.js`:
-
-```js
-module.exports = {
-  target: 'serverless',
-}
-```
-
-## Related
-
-<div class="card">
-  <a href="/docs/api-reference/next.config.js/introduction.md">
-    <b>Introduction to next.config.js:</b>
-    <small>Learn more about the configuration file used by Next.js.</small>
-  </a>
-</div>
-
-<div class="card">
-  <a href="/docs/deployment.md">
-    <b>Deployment:</b>
-    <small>Compile and deploy your Next.js app to production.</small>
-  </a>
-</div>

docs/api-reference/next.config.js/compression.md

@@ -4,7 +4,7 @@ description: Next.js provides gzip compression to compress rendered content and
 
 # Compression
 
-Next.js provides [**gzip**](https://tools.ietf.org/html/rfc6713#section-3) compression to compress rendered content and static files. Compression only works with the [`server` target](/docs/api-reference/next.config.js/build-target.md#server-target). In general you will want to enable compression on a HTTP proxy like [nginx](https://www.nginx.com/), to offload load from the `Node.js` process.
+Next.js provides [**gzip**](https://tools.ietf.org/html/rfc6713#section-3) compression to compress rendered content and static files. In general you will want to enable compression on a HTTP proxy like [nginx](https://www.nginx.com/), to offload load from the `Node.js` process.
 
 To disable **compression**, open `next.config.js` and disable the `compress` config:
 

docs/manifest.json

@@ -292,10 +292,6 @@
               "title": "CDN Support with Asset Prefix",
               "path": "/docs/api-reference/next.config.js/cdn-support-with-asset-prefix.md"
             },
-            {
-              "title": "Build Target",
-              "path": "/docs/api-reference/next.config.js/build-target.md"
-            },
             {
               "title": "Custom Webpack Config",
               "path": "/docs/api-reference/next.config.js/custom-webpack-config.md"