InnerSource Portal updates regarding Santander Bank use case (#391)

* Add Santander Portal screenshot

Author: jesusalonsogut

assets/img/santander_portal.png

@@ -73,6 +73,8 @@ A [reference implementation](https://github.com/SAP/project-portal-for-innersour
 * **American Airlines** promotes InnerSource projects via an [internal InnerSource Marketplace](https://tech.aa.com/2020-10-30-innersource/). Similarly to SAP, projects self-register by adding `innersource` as a GitHub topic. Projects are searchable and filterable by language, topics, number of open issues, etc.
 * **Banco Santander** has created a public portal called [Santander ONE Europe InnerSource Community](https://innersourceportal.santander.com/) to support and increase InnerSource adoption. In addition to the catalog of projects the portal includes relevant content such as documentation, way of working, news, and events.
 
+![Santander InnerSource Portal](../../assets/img/santander_portal.png "Banco Santander InnerSource Portal")
+
 ## References
 
 * The InnerSource Portal pattern has been proven to work extremely well with the associated InnerSource [Gig Marketplace](./gig-marketplace.md) pattern in this context