[docs] Add "Migration" section to sidebar and revise v4-v5 content

CHANGELOG.md

@@ -2598,7 +2598,7 @@ _Sep 1, 2021_
 A big thanks to the 18 contributors who made this release possible. Here are some highlights ✨:
 
 - 🎉 Renamed packages to `@mui/*` as part of rebranding the company, following the strategy of expanding the library scope beyond Material Design. For more details about it, check the [GitHub discussion](https://github.com/mui/material-ui/discussions/27803).
-- 🛠 Added `mui-replace` codemod for migrating `@material-ui/*` to new packages `@mui/*`. Check out this [codemod detail](https://github.com/mui/material-ui/blob/next/packages/mui-codemod/README.md#mui-replace) or head to [migration guide](https://mui.com/material-ui/guides/migration-v4/#preset-safe)
+- 🛠 Added `mui-replace` codemod for migrating `@material-ui/*` to new packages `@mui/*`. Check out this [codemod detail](https://github.com/mui/material-ui/blob/next/packages/mui-codemod/README.md#mui-replace) or head to [migration guide](https://mui.com/material-ui/migration/migration-v4/#preset-safe)
 - 🧪 Added new `<Mansory>` component to the lab, [check it out](https://mui.com/components/masonry/). It has been crafted by our first intern, @hbjORbj 👏!
 
 ### `@mui/material@5.0.0-rc.0`
@@ -4003,7 +4003,7 @@ A big thanks to the 16 contributors who made this release possible. Here are som
   />
   ```
 
-> Follow [this link](https://mui.com/material-ui/guides/migration-v4/#main-content) for full migration from v4 => v5
+> Follow [this link](https://mui.com/material-ui/migration/migration-v4/) for full migration from v4 => v5
 
 #### Changes
 

CHANGELOG.old.md

@@ -3853,7 +3853,7 @@ We will focus or effort on the stability of the library for the next two weeks.
 We don't plan more breaking changes, at the exception of changes that are required to fix bugs or that have minor impacts.
 We hope we can release v4 on May 15th, one year after v1.
 
-Please try the beta out! You can find an [upgrade guide](https://mui.com/material-ui/guides/migration-v3/) to ease the transition.
+Please try the beta out! You can find an [upgrade guide](https://mui.com/material-ui/migration/migration-v3/) to ease the transition.
 You will learn more about v4 in the final release blog post and our plans for the future.
 
 ### `@material-ui/core@v4.0.0-beta.0`
@@ -3988,7 +3988,7 @@ Here are the last breaking changes we want to introduce:
 
 We have done a lot of changes in the alpha phase.
 The beta phase will be used to stabilize the library, we might have introduced bugs.
-We will encourage people to try the beta out. We hope the migration will be smooth [with the upgrade guide](https://mui.com/material-ui/guides/migration-v3/).
+We will encourage people to try the beta out. We hope the migration will be smooth [with the upgrade guide](https://mui.com/material-ui/migration/migration-v3/).
 
 We hope 2-3 weeks of beta will be enough. We plan on releasing v4 stable in May.
 

README.md

@@ -48,9 +48,9 @@ yarn add @mui/material @emotion/react @emotion/styled
 <details>
   <summary>Older versions</summary>
 
-- **[v4.x](https://v4.mui.com/)** ([Migration from v4 to v5](https://mui.com/material-ui/guides/migration-v4/))
-- **[v3.x](https://v3.mui.com/)** ([Migration from v3 to v4](https://mui.com/material-ui/guides/migration-v3/))
-- **[v0.x](https://v0.mui.com/)** ([Migration to v1](https://mui.com/material-ui/guides/migration-v0x/))
+- **[v4.x](https://v4.mui.com/)** ([Migration from v4 to v5](https://mui.com/material-ui/migration/migration-v4/))
+- **[v3.x](https://v3.mui.com/)** ([Migration from v3 to v4](https://mui.com/material-ui/migration/migration-v3/))
+- **[v0.x](https://v0.mui.com/)** ([Migration to v1](https://mui.com/material-ui/migration/migration-v0x/))
 
 </details>
 

docs/data/material/components/hidden/hidden.md

@@ -9,7 +9,8 @@ githubLabel: 'component: Hidden'
 # Hidden
 
 :::error
-`Hidden` is deprecated, checkout [migration docs](/material-ui/guides/migration-v4/#hidden)
+`Hidden` was deprecated in Material UI v5.
+To learn more, see [the `Hidden` section](/material-ui/migration/v5-component-changes/#hidden) of the migration docs.
 :::
 
 <p class="description"></p>

docs/data/material/guides/interoperability/interoperability.md

@@ -766,8 +766,7 @@ if you like the hook-based API (`makeStyles` → `useStyles`) that [`react-jss`]
 TypeScript support than JSS.
 
 :::info
-If you are updating from `@material-ui/core` (v4) to `@mui/material` (v5) checkout
-[migration guide](/material-ui/guides/migration-v4/#2-use-tss-react).
+If you are updating from `@material-ui/core` (v4) to `@mui/material` (v5), check out the [tss-react section](/material-ui/migration/migrating-from-jss/#2-use-tss-react) of the Migration guide.
 :::
 
 ```tsx