docs: enhance documentation at readme file

Signed-off-by: Otavio Santana <otaviopolianasantana@gmail.com>

README.adoc

@@ -5,7 +5,7 @@ image::http://www.jnosql.org/img/logos/ArangoDB.png[ArangoDB, width=200px]
 
 **ArangoDB**: ArangoDB is a native multi-model database system developed by triAGENS GmbH. The database system supports three important data models (key/value, documents, graphs) with one database core and a unified query language AQL (ArangoDB Query Language). The query language is declarative and allows the combination of different data access patterns in a single query. ArangoDB is a NoSQL database system but AQL is similar in many ways to SQL.
 
-==== How to install with Docker
+== How to install with Docker
 
 
 image::https://d1q6f0aelx0por.cloudfront.net/product-logos/library-docker-logo.png[]