docs(basic-usage): explain options, read-replication and dialects

.esdoc.json

@@ -25,7 +25,8 @@
     "asset": "./docs/images",
     "badge": false,
     "installation": [
-      "./docs/getting-started.md"
+      "./docs/getting-started.md",
+      "./docs/usage.md"
     ],
     "tutorial": [
       "./docs/models-definition.md",

docs/scopes.md

 # Scopes
+
 Scoping allows you to define commonly used queries that you can easily use later. Scopes can include all the same attributes as regular finders, `where`, `include`, `limit` etc.
 
 ## Definition

docs/usage.md

-## Basic usage
+# Basic usage
 
 To get the ball rollin' you first have to create an instance of Sequelize. Use it the following way: