R标题的降价指数

Question

I have seen people that are able to create an index based on the titles that you have on your R markdown document like in this picture

If somebody could let me know how would I have to modify this code so it creates that left index table?

---
title: "Untitled"
author: "Juan Lozano"
date: "October 19, 2018"
output: html_document
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
```

## Title 1

Text Text Text Text Text

```{r cars}
summary(cars)
```

## Title 2

Text Text Text Text Text

Answer 1

As @hrbrmstr 's link indicates there are many YAML customisations possible: This is the sort of thing I usually use:

---
title: "Untitled"
author: "john Smith"
date: "today ;)"
output:
  html_notebook:
    fig_caption: yes
    number_sections: yes
    toc: yes
    toc_float: yes
  html_document:
    fig_caption: yes
    number_sections: yes
    toc: yes
    toc_float: yes
    df_print: paged
bibliography: /path/to/library.bib
---