I set up a Cart Price Rule that gives 30% discount. The 30% discount is given to the order, however, it displays "Discount" instead of the Default Rule Label specified. 

## Cart Price Rule Setup
The following is details to the Rule I added: 
[![enter image description here][1]][1]
[![enter image description here][2]][2]
[![enter image description here][3]][3]
[![enter image description here][4]][4]


## Frontend
Even though the labels were set, it shows Discount in the front end
[![enter image description here][5]][5]


## Edit: 
With more research I saw that the variable "Discount" is passed to the Knockout JS discount.html template instead of the Discount Description. 

`module-sales-rule/view/frontend/layout/checkout_cart_index.xml`

    <?xml version="1.0"?>
    <page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
        <body>
            <referenceBlock name="checkout.cart.totals">
                <arguments>
                    <argument name="jsLayout" xsi:type="array">
                        <item name="components" xsi:type="array">
                            <item name="block-totals" xsi:type="array">
                                <item name="children" xsi:type="array">
                                    <item name="before_grandtotal" xsi:type="array">
                                        <item name="children" xsi:type="array">
                                            <item name="discount" xsi:type="array">
                                                <item name="component"  xsi:type="string">Magento_SalesRule/js/view/cart/totals/discount</item>
                                                <item name="config" xsi:type="array">
                                                    <item name="title" xsi:type="string" translate="true">Discount</item>
                                                </item>
                                            </item>
                                        </item>
                                    </item>
                                </item>
                            </item>
                        </item>
                    </argument>
                </arguments>
            </referenceBlock>
        </body>
    </page>


  [1]: https://i.sstatic.net/IWUwg.png
  [2]: https://i.sstatic.net/dSg0P.png
  [3]: https://i.sstatic.net/OvErx.png
  [4]: https://i.sstatic.net/MFyiv.png
  [5]: https://i.sstatic.net/W8ozP.png