[SYNC] docs: rephrase version pinning

[github-actions[bot]]

docs: rephrase version pinning (00e6af3)

---

+++ b/docs/.vitepress/config.ts
@@ -1,12 +1,60 @@
-import { defineConfig } from 'vitepress'
+import { defineConfig, DefaultTheme } from 'vitepress'
const ogDescription = 'Next Generation Frontend Tooling'
const ogImage = 'https://vitejs.dev/og-image.png'
const ogTitle = 'Vite'
const ogUrl = 'https://vitejs.dev'
+// netlify envs
+const deployURL = process.env.DEPLOY_PRIME_URL || ''
+const commitRef = process.env.COMMIT_REF?.slice(0, 8) || 'dev'
+
+const deployType = (() => {
+  switch (deployURL) {
+    case 'https://main--vite-docs-main.netlify.app':
+      return 'main'
+    case '':
+      return 'local'
+    default:
+      return 'release'
+  }
+})()
+const additionalTitle = ((): string => {
+  switch (deployType) {
+    case 'main':
+      return ' (main branch)'
+    case 'local':
+      return ' (local)'
+    case 'release':
+      return ''
+  }
+})()
+const versionLinks = ((): DefaultTheme.NavItemWithLink[] => {
+  switch (deployType) {
+    case 'main':
+    case 'local':
+      return [
+        {
+          text: 'Vite 3 Docs (release)',
+          link: 'https://vitejs.dev'
+        },
+        {
+          text: 'Vite 2 Docs',
+          link: 'https://v2.vitejs.dev'
+        }
+      ]
+    case 'release':
+      return [
+        {
+          text: 'Vite 2 Docs',
+          link: 'https://v2.vitejs.dev'
+        }
+      ]
+  }
+})()
+
export default defineConfig({
-  title: 'Vite',
+  title: `Vite${additionalTitle}`,
description: 'Next Generation Frontend Tooling',
head: [
@@ -62,7 +110,7 @@ export default defineConfig({
},
footer: {
-      message: 'Released under the MIT License.',
+      message: `Released under the MIT License. (${commitRef})`,
copyright: 'Copyright © 2019-present Evan You & Vite Contributors'
},
@@ -106,12 +154,7 @@ export default defineConfig({
},
{
text: 'Version',
-        items: [
-          {
-            text: 'Vite 2 Docs',
-            link: 'https://v2.vitejs.dev'
-          }
-        ]
+        items: versionLinks
}
],