feat-req: Guide on how to upgrade versions

[SSmale]

I saw that you had released v4 but I could not find a guide on how to upgrade. when I tried to merge the changes in I got an error about no shared history.

to get mine upgraded I think I did the followinng steps:

1. checkout the upgrade code
2. create a new branch and delete everything BUT the .git dir
3. copy all the files in from the upgraded branch into the now empty directory
4. use the diff to revert, stage or combine the changes.

[benjaminrae]

When you get that error you can merge with the --allow-unrelated-histories flag and then you just need to to resolve the conflicts.