reword first bullet in section 2.3

[gilch]

It currently reads:

First, if either u or v is an lvar, the unifying them with a value just like assigning a value to that lvar in the substitution map.

I'm not sure what it means; my best guess:

First, if either u or v is an lvar, then unifying them with a value is just like assigning a value to that lvar in the substitution map.