Add document about libraries structure

docs/main/introduction/introduction_.rst

@@ -1,45 +0,0 @@
-Key features
-------------
-
-*Dependency Injector* is a dependency injection framework for Python projects. 
-It was designed to be unified, developer's friendly tool for managing any kind
-of Python objects and their dependencies in formal, pretty way.
-
-Below is a list of some key features and points of *Dependency Injector*
-framework:
-
-- Easy, smart, pythonic style.
-- Obvious, clear structure.
-- Memory efficiency.
-- Semantic versioning.
-
-Main idea of *Dependency Injector* is to keep dependencies under control.
-
-Main entities
--------------
-
-Current section describes *Dependency Injector* main entities and their 
-interaction with each other.
-
-.. image:: /images/internals.png
-    :width: 100%
-    :align: center
-
-There are 3 main entities:
-
-- Providers. Providers are strategies of accesing objects. For example, 
-  :py:class:`dependency_injector.providers.Factory` creates new instance of 
-  provided class every time it is called. 
-  :py:class:`dependency_injector.providers.Singleton` creates provided 
-  instance once and returns it on every next call. Providers could be 
-  overridden by another providers. Base class is - 
-  :py:class:`dependency_injector.providers.Provider`.
-- Injections. Injections are instructions for making dependency injections 
-  (there are several ways how they could be done). Injections are used mostly
-  by :py:class:`dependency_injector.providers.Factory` and 
-  :py:class:`dependency_injector.providers.Singleton` providers, but 
-  these are not only cases. Base class is - 
-  :py:class:`dependency_injector.injections.Injection`.
-- Catalogs. Catalogs are collections of providers. They are used for grouping 
-  of providers by some principles. Base class is - 
-  :py:class:`dependency_injector.catalogs.DeclarativeCatalog`.

docs/main/introduction/structure.rst

@@ -1,2 +1,42 @@
 Structure of Dependency Injector
 --------------------------------
+
+Current section describes *Dependency Injector* main entities and their 
+interaction between each other.
+
+.. image:: /images/internals.png
+    :width: 100%
+    :align: center
+
+There are 3 main entities:
+
+.. glossary::
+
+    Providers
+        Providers are strategies of accesing objects. For example, 
+        :py:class:`dependency_injector.providers.Factory` creates new instance 
+        of provided class every time it is called. 
+        :py:class:`dependency_injector.providers.Singleton` creates provided 
+        instance once and returns it on every next call. Providers could be 
+        injected into each other. Providers could be overridden by another 
+        providers. Base class is - 
+        :py:class:`dependency_injector.providers.Provider`.
+
+    Injections
+        Injections are instructions for making dependency injections 
+        (there are several ways how they could be done). Injections are used 
+        mostly by :py:class:`dependency_injector.providers.Factory` and 
+        :py:class:`dependency_injector.providers.Singleton` providers, but 
+        these are not only cases. Base class is - 
+        :py:class:`dependency_injector.injections.Injection`.
+
+    Catalogs 
+        Catalogs are collections of providers. They are used for grouping 
+        of providers by some principles. Base class is - 
+        :py:class:`dependency_injector.catalogs.DeclarativeCatalog`.
+
+Some general principles about *Dependency Injector* entities:
+
++ All of the entities could be used in composition with each other or 
+  separatelly.
++ Each of the entities could be extended via specialization.