shinydashboard - "Get started" Tab [1 Link + 1 Typo]

[Two problems were detected](https://rstudio.github.io/shinydashboard/get_started.html)

1) The link is broken

![link](https://github.com/rstudio/shinydashboard/assets/102655648/d9fa2b45-dd88-49df-b928-6c8b0cd6f117)

2) Typo

![typo](https://github.com/rstudio/shinydashboard/assets/102655648/a2934300-8602-4e7d-bfba-95db28e3cfa3)
