If the readme looks like this:
(https://i.imgur.com/daYevbY.png)
Then it's because the file is encoded in Shift-JIS and your computer doesn't have the Japanese settings installed to read it. If you download Notepad++ (an awesome text editor that everyone should use instead of Notepad anyway) then you can specify the encoding yourself:
(https://i.imgur.com/l3i8SO8.png)
And then it should look like actual Japanese text!
(https://i.imgur.com/py8gyw4.png)
You can then copy this into google translate to see what it means.
(https://i.imgur.com/cfBdLjC.png)