docs(guide/overview): Refactor overview and mvc docs

Before, there we multiple overview docs:
- guide/overview
- guide/introduction
- guide/dev_guide.mvc
- guide/dev_guide.mvc.understanding_model
- guide/dev_guide.mvc.understanding_view
- guide/concepts

Now we have:
- guide/introduction: High level description of Angular with the key benefits but without code or any concrete concepts
- guide/concepts: explains all important concepts with a simple example and contains deep links to the other parts of the guide.

 All the old information was moved into existing documents or deleted when they were duplicates.

1 files changed, 11 insertions, 0 deletions

diff --git a/docs/content/api/index.ngdoc b/docs/content/api/index.ngdoc
index 48011e47..3a1b361a 100644
--- a/docs/content/api/index.ngdoc
+++ b/docs/content/api/index.ngdoc
@@ -8,6 +8,17 @@ Welcome to the AngularJS API docs page. These pages contain the AngularJS refere
 The documentation is organized into **modules** which contain various components of an AngularJS application.
 These components are directives, services, filters, providers, types, global APIs and testing mocks.
 
+<div class="alert alert-info">
+**Angular Namspaces `$` and `$$`**
+
+To prevent accidental name collisions with your code,
+Angular prefixes names of public objects with `$` and names of private objects with `$$`.
+Please do not use the `$` or `$$` prefix in your code.
+</div>
+
+## Angular Namespace
+
+
 ## {@link ng ng (core module)}
 This module is provided by default and contains the core components of AngularJS.