Create Invoice templates and Send invoices automatically inside workflows

• This needs to be enabled at the account level by heading under Settings -> Labs and turning the toggle on for the feature. 
• Users will be able to convert any invoice created into a template using the Convert to Template action and give an appropriate name to it for future references.
•  Templates can contain all information related to business information, logo, invoice title, product line items, taxes, discounts, and terms. 
• Customer information will be populated along with the issue date and due date while sending the invoice as per the invoice settings. 
• All templates will be listed on the Templates page under the Invoicing section. Quick actions on the templates page will enable the use of the template as a one-time invoice or a recurring invoice. 
• Users will be able to modify, rename, or delete the templates at any point in time.

Business users will be able to make use of the same templates to send an invoice in a workflow using the Send Invoice action.

•  Users will be able to make use of the templates created inside the invoice module to define the invoice details that need to go out to the customer
• Turn the feature on in Labs under account settings. 
• Business users will be able to configure the action name, select the From User to define the sender details, and choose a template from one of the templates created inside invoices along with the payment mode. 
• The default/custom template configured inside the invoice settings will be used automatically to send the invoice from workflows as well.
•  This fulfills a lot of use cases like sending an invoice after an appointment is booked, opportunity status is changed, tag is attached to a contact or any other trigger existing.