Update README (add banner and about us)

Author: ecorica

.github/banner-github.png

@@ -1,3 +1,5 @@
+<a href="https://beapi.fr">![Be API Github Banner](.github/banner-github.png)</a>
+
 #  BeAPI FrontEnd Framework
 ![Node.js CI](https://github.com/BeAPI/beapi-frontend-framework/workflows/Node.js%20CI/badge.svg?branch=master)
 
@@ -276,4 +278,12 @@ We add Lazyload support too! We use [Lazysize](https://github.com/aFarkas/lazysi
 
 If you don't want this feature you still can set BEA_LAZYSIZE to false in /functions/class-bea-images.php. it will turn the markup to basic img tag with srcset.
 
-Lazysize is also used for displaying background image in different sizes for differents viewports. Look at the Lazysize bgset documentation and the `page__header` or `hero` pattern.
+Lazysize is also used for displaying background image in different sizes for differents viewports. Look at the Lazysize bgset documentation and the `page__header` or `hero` pattern.
+
+# Who ?
+
+Created by [Be API](https://beapi.fr), the French WordPress leader agency since 2009. Based in Paris, we are more than 30 people and always [hiring](https://beapi.workable.com) some fun and talented guys. So we will be pleased to work with you.
+
+This plugin is only maintained, which means we do not guarantee some free support. Consider reporting an [issue](#issues--features-request--proposal) and be patient.
+
+If you really like what we do or want to thank us for our quick work, feel free to [donate](https://www.paypal.me/BeAPI) as much as you want / can, even 1€ is a great gift for buying coffee :)