update pairing-in-phase-0 to make driver/navigator role more flexible.

I think it's a good start, but could have some more info. what about something like:
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The navigator needs to keep their eyes on the big picture of the code. Because they aren't typing, they can catch syntax errors, research quickly, review the docs for reference, etc. The navigator's role in the development of the program is the same as the driver, they just do not type unless they ask for permission and are granted it. Navigators should also avoid being too specific about what needs to be typed. The navigator should be specific without telling the driver EXACTLY how to write the code. For example:

"Initialize a method that accepts two arguments" 

is preferable to 

"Type def method name open parenthesis arg1 comma arg2 close parenthesis"