[refactor] project documentation

Note: The structure is subject of change and proposal are welcome

Here is proposal for documentation restructure:

Getting Started
- First Steps
- Importing UI5 Web Components
- Understanding UI5 Web Components APIs
- Wrapping Up
Advanced Concepts
- Configuration
- Right-To-Left (RTL) and Compact Mode
- Icons
- Reusable styles
- Assets
- Features
- Scoping
- OpenUI5 Integration
- UI5 Web Components i18n for Apps
- Accessibility
- CSP
- Scrollbars customisation
- Ignore Custom HTML elements
- Styling
  - Shadow Parts
  - CSS Variables
  - Custom theme (ui theme designed / custom theme)
- Theming
Framework integration
- Overview
- React
- Angular
- Vue
- Svelte
Component development
- API
  - Metadata
  - Lifecycle hooks
- Lifecycle hooks
  - onBeforeRendering
  - onAfterRendering
  - onEnterDOM
  - onExitDOM
- Component
  - @customElement decorator
    - languageAware
    - themeAware
    - formAssociated
    - fastNavigation
- Properties
  - @property decorator
- Slots
  - @slot decorator
    - Different slot types
      - Managed slots
      - Unnamed slots
- Events
  - @event decorator
- Styling
- i18n support
- Template
- Renering engine
- Testing
- Deep dive and best practices
Contributing to the UI5 Web Components Project
- General Development Workflow
- Development Conventions and Guidelines
- Using Website Locally
Frequently Asked Questions
Release Management

SAP / ui5-webcomponents