Documentation update [ci-skip]

Author: kzaitsev

README.md

@@ -29,7 +29,8 @@ These screenshot is based on the [Hussars](https://github.com/LeFnord/hussars) s
 
 ## Model Parsers
 
-Since 0.21.0, `Grape::Entity` is not a part of grape-swagger, you need to add `grape-swagger-entity` manually to your Gemfile:
+Since 0.21.0, `Grape::Entity` is not a part of grape-swagger, you need to add `grape-swagger-entity` manually to your Gemfile.
+Also added support for [representable](https://github.com/apotonick/representable) via `grape-swagger-representable`.
 
 ```ruby
 # For Grape::Entity ( https://github.com/ruby-grape/grape-entity )
@@ -38,6 +39,60 @@ gem 'grape-swagger-entity'
 gem 'grape-swagger-representable'
 ```
 
+##### Custom model parser interface
+
+You can create yuor own model parser, for example for [roar](https://github.com/apotonick/roar)
+
+```rb
+module GrapeSwagger
+  module Roar
+    class Parser
+      attr_reader :model
+      attr_reader :endpoint
+
+      def initialize(model, endpoint)
+        @model = model
+        @endpoint = endpoint
+      end
+
+      def call
+        # Parse your model and return hash with model schema for swagger
+      end
+    end
+  end
+end
+```
+
+Then you should register your custom parser:
+
+```rb
+GrapeSwagger.model_parsers.register(GrapeSwagger::Roar::Parser, Roar::Decorator)
+```
+
+To controll model parsers sequence, you can insert your Parser before or after another parser
+
+before:
+
+```rb
+if defined?(GrapeSwagger::Representable::Parser)
+  GrapeSwagger.model_parsers.insert_before(GrapeSwagger::Representable::Parser, GrapeSwagger::Roar::Parser, Roar::Decorator)
+else
+  GrapeSwagger.model_parsers.register(GrapeSwagger::Roar::Parser, Roar::Decorator)
+end
+```
+
+after:
+
+```rb
+if defined?(GrapeSwagger::Roar::Parser)
+  GrapeSwagger.model_parsers.insert_after(GrapeSwagger::Roar::Parser, GrapeSwagger::Representable::Parser, Representable::Decorator)
+else
+  GrapeSwagger.model_parsers.register(GrapeSwagger::Representable::Parser, Representable::Decorator)
+end
+```
+
+As we know, `Roar::Decorator` uses as superclass `Representable::Decorator`, this allow to avoid problem when Roar objects will be processed by `GrapeSwagger::Representable::Parser`, instead `GrapeSwagger::Roar::Parser`
+
 <a name="related" />
 ## Related Projects
 
@@ -53,13 +108,13 @@ gem 'grape-swagger-representable'
 
 The following versions of grape, grape-entity and grape-swagger can currently be used together.
 
-grape-swagger | swagger spec | grape                   | grape-entity
---------------|--------------|-------------------------|-------------
-0.10.5        |     1.2      | >= 0.10.0 ... <= 0.14.0 |  < 0.5.0
-0.11.0        |     1.2      |               >= 0.16.2 |  < 0.5.0
-0.20.1        |     2.0      | >= 0.12.0 ... <= 0.14.0 | <= 0.5.1
-0.20.3        |     2.0      | >= 0.12.0 ... ~> 0.16.2 | ~> 0.5.1
-0.21.0 (next) |     2.0      | >= 0.12.0 ... <= 0.16.2 | <= 0.5.1
+grape-swagger | swagger spec | grape                   | grape-entity | rerpresentable |
+--------------|--------------|-------------------------|--------------------------------
+0.10.5        |     1.2      | >= 0.10.0 ... <= 0.14.0 |  < 0.5.0     | Unsupported
+0.11.0        |     1.2      |               >= 0.16.2 |  < 0.5.0     | Unsupported
+0.20.1        |     2.0      | >= 0.12.0 ... <= 0.14.0 | <= 0.5.1     | Unsupported
+0.20.3        |     2.0      | >= 0.12.0 ... ~> 0.16.2 | ~> 0.5.1     | Unsupported
+0.21.0 (next) |     2.0      | >= 0.12.0 ... <= 0.16.2 | <= 0.5.1     | >= 2.4.1
 
 <a name="swagger-spec" />
 ## Swagger-Spec