Improve English

Various minor tweaks to the English in the README file.

Let me know if you have any questions about the changes I've made. I'm not an expert on English, I just use it every day! :confounded: 

I changed "right?" to "do you?" in "You don't want to mix up your changes and Transpec's changes, do you?". I suspect that "right?" is used for positive form, and "do you?" is used for the negative form. For example, I think you'd say

    "You want to come to Taiwan, right?"

but

    "You don't want to forget your passport, do you?"