Enable rerere (Reuse Recorded Resolution)

This line will enable rerere

```
git config --global rerere.enabled true
```

See 

- https://medium.com/@porteneuve/fix-conflicts-only-once-with-git-rerere-7d116b2cec67
- https://www.git-scm.com/book/en/v2/Git-Tools-Rerere

I think we should enable this feature