fix: replaced dead links (#2567)

Fixes dead links in the Assets documentation page and replaces with
working links. Fixes #2566 .

### Change Type

- [ ] `patch` — Bug fix
- [ ] `minor` — New feature
- [ ] `major` — Breaking change
- [ ] `dependencies` — Changes to package dependencies[^1]
- [x] `documentation` — Changes to the documentation only[^2]
- [ ] `tests` — Changes to any test code only[^2]
- [ ] `internal` — Any other changes that don't affect the published
package[^2]
- [ ] I don't know

[^1]: publishes a `patch` release, for devDependencies use `internal`
[^2]: will not publish a new version

### Test Plan

None required. 

- [ ] Unit Tests
- [ ] End to end tests

### Release Notes

- N/A

Co-authored-by: Steve Ruiz <steveruizok@gmail.com>

apps/docs/content/docs/assets.mdx

@@ -21,6 +21,6 @@ You can use assets for any shared piece of information, however they're best use
 
 While we're working on docs for this part of the project, please refer to the examples below:
 
-- [Using images hosted](https://github.com/tldraw/tldraw/blob/main/apps/examples/src/examples/HostedImagesExample.tsx)
-- [Customizing the default asset options](https://github.com/tldraw/tldraw/blob/main/apps/examples/src/examples/AssetOptionsExample.tsx)
-- [Handling pasted / dropped external content](https://github.com/tldraw/tldraw/blob/main/apps/examples/src/examples/ExternalContentSourcesExample.tsx)
+- [Using images hosted](https://github.com/tldraw/tldraw/blob/main/apps/examples/src/examples/hosted-images/HostedImagesExample.tsx)
+- [Customizing the default asset options](https://github.com/tldraw/tldraw/blob/main/apps/examples/src/examples/asset-props/AssetPropsExample.tsx)
+- [Handling pasted / dropped external content](https://github.com/tldraw/tldraw/blob/main/apps/examples/src/examples/external-content-sources/ExternalContentSourcesExample.tsx)