Renaming in file in explorer does not rename its reference in markdown

Testing #147738

1. Open the following file in markdown https://github.com/microsoft/vscode-docs/blob/vnext/release-notes/June_2016.md#L22
2. Add the following content
```
[link](./July_2016.md)
```
3. Open Explorer, rename the file `July_2016.md`. The link in markdown does not get updated 🐛 