Add serialization guide to the docs

docs/Configuration.md

 # Configuration
 
-Dependency injection is used for configuration using the ```dependency_injector``` package.
-Configuration files can be in json or ini format.
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+Models can be serialized as a ```json``` file with the following structure:
+
+```json
+{
+  "model": {
+    "type": <model_type>,
+    "parameters": {
+      <parameter_name>: {
+        "type": <class_name>,
+        "parameters": {...}
+      }
+    }
+  }
+}
+```
+
+The ```"type"``` field serves as a dependency-injection like mechanism and
+sets which class and constructor is used.
+The ```"parameters"``` dictionary is passed to the constructor method. Every
+parameter is attempted to be resolved from the class registry and only if that's
+not possible they are passed as-is.
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