Update Readme with awWizardStepSymbol explanation (#155)
Update Readme with awWizardStepSymbol explanation (#155)

- add a short explanation to the README for the awWizardStepSymbol directive
- fix #151
- specify, that angular-archwizard should be used with angular 5+
- remove the now obsolete information, that ng-template has been added in angular 4

madoar/ng2-wizard,madoar/ng2-archwizard,madoar/ng2-archwizard,madoar/ng2-wizard,madoar/ng2-archwizard,madoar/ng2-wizard