docs: page about esbuild plugin

Author: joelgallant

docs/.vuepress/config.js

@@ -55,6 +55,10 @@ module.exports = {
         title: 'Rollup',
         path: '/guide/rollup',
       },
+      {
+        title: 'esbuild',
+        path: '/guide/esbuild',
+      },
       {
         title: 'Electron',
         path: '/guide/electron',

docs/guide/esbuild.md

@@ -0,0 +1,36 @@
+---
+title: esbuild Bundler Plugin
+---
+
+::: tip Before Reading
+Head on over to the [Introduction](../intro/) or [Quick Start](../intro/quick-start) if you haven't already.
+:::
+
+The esbuild plugin is a separate package, which you'll need to install:
+
+```sh
+yarn add -D @app-config/esbuild@2
+```
+
+Then add it to your esbuild configuration:
+
+```javascript
+const { createPlugin: appConfig } = require('@app-config/esbuild');
+
+require('esbuild')
+  .build({
+    bundle: true,
+    entryPoints: ['./src/index.ts'],
+    outfile: './dist/index.js',
+    // this is the line we care about
+    plugins: [appConfig()],
+  })
+  .catch(() => process.exit(1));
+```
+
+This will allow you to import `@app-config/main` from your application, with all
+filesystem and other Node.js code stripped out (when using `bundle`).
+
+```javascript
+import config from '@app-config/main';
+```