docs(migration): restructure upgrade guide (#7730)

docs/content/1.getting-started/10.upgrade.md

@@ -0,0 +1,59 @@
+# Upgrade Guide
+
+Have a Nuxt 2 project to migrate? Use these guides to upgrade your Nuxt applications to Nuxt 3 or take the first step in that direction with Nuxt Bridge.
+
+If you are already using Nuxt 3 and want to upgrade to the latest release or test new features before their release, head over to the [Upgrading Nuxt 3](#upgrading-nuxt-3) section.
+
+## Feature Comparison
+
+In the table below, there is a quick comparison between 3 versions of Nuxt:
+
+Feature / Version        | Nuxt 2          | Nuxt Bridge      | Nuxt 3
+-------------------------|-----------------|------------------|---------
+Vue                      | 2               | 2                | 3
+Stability                | 😊 Stable      | 😌 Semi-stable    | Release candidate
+Performance              | 🏎 Fast        | ✈️ Faster          | 🚀 Fastest
+Nitro Engine             | ❌             | ✅                | ✅
+ESM support              | 🌙 Partial     | 👍 Better         | ✅
+TypeScript               | ☑️ Opt-in       | 🚧 Partial        | ✅
+Composition API          | ❌             | 🚧 Partial        | ✅
+Options API              | ✅             | ✅                | ✅
+Components Auto Import   | ✅             | ✅                | ✅
+`<script setup>` syntax  | ❌             | 🚧 Partial        | ✅
+Auto Imports             | ❌             | ✅                | ✅
+Webpack                  | 4              | 4                 | 5
+Vite                     | ⚠️ Partial      | 🚧 Partial        | ✅
+Nuxi CLI                 | ❌ Old         | ✅ nuxi           | ✅ nuxi
+Static sites             | ✅             | ✅                | ✅
+
+## Nuxt 2 to Nuxt 3
+
+The migration guide provides a step-by-step comparison of Nuxt 2 features to Nuxt 3 features and guidance to adapt your current application.
+
+::alert{type=info icon=👉}
+[**Migrate from From Nuxt 2 to Nuxt 3**](/migration/overview)
+::
+
+## Nuxt 2 to Nuxt Bridge
+
+If you prefer to progressively migrate your Nuxt 2 application to Nuxt 3, you can use Nuxt Bridge. Nuxt Bridge is a compatibility layer that allows you to use Nuxt 3 features in Nuxt 2 with an opt-in mechanism.
+
+::alert{type=info icon=👉}
+[**Migrate from Nuxt 2 to Nuxt Bridge**](/bridge/overview)
+::
+
+## Upgrading Nuxt 3
+
+### Latest release
+
+To upgrade Nuxt 3 to the latest release, use the `nuxi upgrade` command.
+
+```bash
+npx nuxi upgrade
+```
+
+### Edge release channel
+
+::alert{type=info icon=👉}
+To use the latest Nuxt 3 build and test features before their release, read the [edge release channel](/guide/going-further/edge-channel) guide.
+::

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