Overall, the gameplay rules are clear. However, you sometimes mention a game operation (repairing cards, in the maintenance phase) before the operation is properly introduced and explained. You might be able to move the explanation up; if not a reference will help.
-- Is there a way to track what combat card is linked to what equip technology card?
-- The footnote hint on how to move a movement 0 card was a little confusing. You might want to introduce it with something, "If you need to move a movement 0 card, here's how." If it's truly a footnote, there should be an asterisk somewhere in the main text leading to it, otherwise you should break the text out with a graphic element such as a box. You should also add a reference to when you can discard cards during your turn.
-- You probably don't need to repeat the golden rule in different sections. Just put a more general statement once near the beginning of the Game Play rules.
-- It looks like you can attack any units on the line in a standard melee attack, not just the ones in front of you. If that's true, you should give this a little more attention -- it makes sense, but it's unusual enough in this kind of game that you should call it out explicitly.
-- Are charge attacks a special ability or something any unit that meets the criteria can do?
-- You're using the "Attack" stat in a defensive context, specifically in lines like "When attacking, if you attack an opponent’s combat card which is your combat card’s strength type, +1 to your attack. If you defend an attack from your opponent’s combat card which is your combat card’s weakness type, +1 to your opponent’s attack." This is pretty confusing, and likely to cause misapplied bonuses. Consider renaming the stat or the action ("battle" and "Attack" might work), and consistently capitalizing this and any other stat you refer to.