1.1: Alerts basic example
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**Primary Actor**: User

**Scope**: Ngx-bootstrap DEMO / BS version 3&4

**Goal**: Show user basic alerts functionality

Main success scenario:
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1. User open Alerts demo page
2. User click on Basic sub-menu
3. User see 4 alerts with types: success, info, warning, danger

Variations:
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2*. User scroll to Basic sub-menu