Restructure documentation

[containerpope]

To allow better user onboarding we should implement the documentation as follows:

Core Docs

1. Introduction
   1.1 Overview
   1.2 Example
   1.2.3 Create Policies
   1.2.4 Configure Kelon
   1.2.5 Run the example
2. Philosophy
   2.1 Why external Policy Enforcement
   2.2 What is a Policy
3. Architecture
   3.1 Components
   3.2 Policy Translation
   3.3 Query-AST
4. Integrating Kelon
   4.1 Services and Kelon
   4.2 Kelon and Gloo
   4.3 Kelon and Istio
5. Extending Kelon
   5.1 Create a new datasource plugin

Operations

1. APIs
2. Configuration
3. Deployment
4. Monitoring
5. Security

Task for restructuring

• Apply initial structure as proposed
• Migrate all docs from old structure into new structure
• Update info graphics containing Query-AST
• Adjust/Simplify example policies
• Make version of Kelon selectable
• Add Dividers in left navigation bar instead of nesting

[containerpope]

@dcseifert what do you think about this structure? Please add your notes into the structure so that we can boostrap this.