Tailwind v2 docs (#4758)

* Add migration notes to Tailwind changelog

* Include `tailwindcss` in manual install steps

* add changeset

.changeset/swift-trees-double.md

@@ -0,0 +1,5 @@
+---
+"@astrojs/tailwind": patch
+---
+
+Update Tailwind manual install guide for v2

packages/integrations/tailwind/CHANGELOG.md

@@ -2,6 +2,14 @@
 
 ## 2.0.0
 
+### Migration to v2
+
+Tailwind CSS is now a peer dependency, so you will need to install it manually when updating this integration:
+
+```
+npm install tailwindcss
+```
+
 ### Major Changes
 
 - [#4543](https://github.com/withastro/astro/pull/4543) [`664ebf449`](https://github.com/withastro/astro/commit/664ebf449e27f0aef43eaa2482189358a74209d2) Thanks [@aFuzzyBear](https://github.com/aFuzzyBear)! - Update peer dep with Tailwindcss

packages/integrations/tailwind/README.md

@@ -42,9 +42,9 @@ If you run into any issues, [feel free to report them to us on GitHub](https://g
 
 ### Manual Install
   
-First, install the `@astrojs/tailwind` package using your package manager. If you're using npm or aren't sure, run this in the terminal:
+First, install the `@astrojs/tailwind` and `tailwindcss` packages using your package manager. If you're using npm or aren't sure, run this in the terminal:
 ```sh
-npm install @astrojs/tailwind
+npm install @astrojs/tailwind tailwindcss
 ```
 Then, apply this integration to your `astro.config.*` file using the `integrations` property: