I don't know why this isn't easier. A way to hack it is to use the author YAML input as the subtitle and use some css to rearrange the title. If you run the following Rmarkdown file, you should see the title now on two lines.
---
title: "Uber data analysis"
author: "(NYC, April 2014 - September 2014)"
output:
flexdashboard::flex_dashboard:
orientation: columns
vertical_layout: fill
---
<style>
.navbar-brand {
display: grid;
margin: auto;
padding: 5px;
}
.navbar-author {
margin-left: 0px;
}
</style>
```{r setup, include=FALSE}
library(flexdashboard)
```
Highlights
========================================
Column
-----------------------------------------------------------------------
### Chart A
```{r}
```
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