Migrating Tailwind setup (#1806)

web/docs/migrate-from-0-11-to-0-12.md

@@ -301,14 +301,65 @@ directory `foo`, you should:
     `foo/.gitignore`
 13. Copy the rest of the top-level files and folders (all of them except for `.gitignore`, `main.wasp` and `src/`)
     in `foo_old/` into `foo/` (overwrite the existing files in `foo`).
-14. Run `wasp clean`.
+14. Run `wasp clean` in `foo`.
+15. Delete the `foo_old` directory.
 
 </div>
 </details>
 
 That's it! You now have a properly structured Wasp 0.12.0 project in the `foo` directory.
-Your app probably doesn't quite work yet due to the breaking changes in Auth, which we will migrate next.
+Your app probably doesn't quite work yet due to some other changes in Wasp 0.12.0, but we'll get to that in the next sections.
 
+### Migrating the Tailwind Setup
+
+:::note
+If you don't use Tailwind in your projet, you can skip this section.
+:::
+
+There is a small change in how the `tailwind.config.cjs` needs to be defined in Wasp 0.12.0. 
+
+You'll need to wrap all your paths in the `content` field with the `resolveProjectPath` function. This makes sure that the paths are resolved correctly when generating your CSS.
+
+Here's how you can do it:
+
+<Tabs>
+<TabItem value="before" label="Before">
+
+```js title="tailwind.config.cjs"
+/** @type {import('tailwindcss').Config} */
+module.exports = {
+  content: [
+    // highlight-next-line
+    './src/**/*.{js,jsx,ts,tsx}',
+  ],
+  theme: {
+    extend: {},
+  },
+  plugins: [],
+}
+```
+</TabItem>
+
+<TabItem value="after" label="After">
+
+```js title="tailwind.config.cjs"
+// highlight-next-line
+const { resolveProjectPath } = require('wasp/dev')
+
+/** @type {import('tailwindcss').Config} */
+module.exports = {
+  content: [
+    // highlight-next-line
+    resolveProjectPath('./src/**/*.{js,jsx,ts,tsx}'),
+  ],
+  theme: {
+    extend: {},
+  },
+  plugins: [],
+}
+```
+</TabItem>
+</Tabs>
 
 ### Migrating to the New Auth
 As shown in [the previous section](#new-auth), Wasp significantly changed how authentication works in version 0.12.0.