Magento2 – Usage of salesrule_coupon Expiration Date Field

I have not found any solution for it, But I have used an alternate way to achieve it.

1. create rule which will be always expired by date.
2. push condition based coupon codes to it based on cron.

code:

$couponCode = 'XZY';//auto-generated code or get collection of auto-generated               codes from a rule.
$oCoupon = Mage::getModel('salesrule/coupon')->load($couponCode, 'code');

$ruleName = 'referral_expired'; //existing rule with this name
$shoppingRule = Mage::getResourceModel('salesrule/rule_collection')->addFieldToFilter('name',$ruleName)->load()->getFirstItem();
$shoppingRuleId = $shoppingRule->getRuleId();
$oCoupon->setData('rule_id',$shoppingRuleId);
$oCoupon->save(); 

The user guide PDF you linked to appears to be out of date. See the equivalent HTML page: http://docs.magento.com/m2/ee/user_guide/marketing/price-rules-cart.html

They removed point 1.6, regarding the date fields, and replaced step 5 with four new steps (5-8).

The answer to your question is in step 8. The date fields are gone, but that's okay, and it's intentional. There's a different way to schedule things now. Magento added a new Enterprise feature called 'Content Staging' in 2.1. All scheduling must be done through the staging feature, rather than on the date fields present on older versions and still on Community Edition.

The benefit is that you can directly link your promotions to changes in product content, banners, pages, etc, and have them all apply and end at the same time. You schedule the changes in advance; Magento takes care of the rest for you.