revealjs: option to show text in the output slide when #| output-location: slide is selected

[Lulliter]

Description

(Related to issues 4213)

In revealjs presentations, when #| output-location: slide is selected, it would be great to have also the option of showing some comments/annotations in the slide where the output is rendered (e.g. a plot). Below is a toy presentation to clarify:

---
title: ""
format: revealjs
---

## Plot comment (falls in the wrong slide)

**Code comment**: Here you can see the code (OK!)  
```{r}
#| echo: true
#| eval: true
#| output-location: slide

library(dplyr)
library(ggplot2)

starwars %>% 
  filter(homeworld == c("Alderaan","Tatooine" )) %>% 
  ggplot( aes(x = height,fill = homeworld))+
  geom_density(alpha = 0.5)  
```

**Plot comment**:  "Here you can see how the distribution of variable `height` is not normal"  

[mcanouil]

Why not write your output in a code cell and use the option?

[Lulliter]

that makes sense! thanks

[mcanouil]

Did not try but you could also emit a regular cross-referenceable figure with a caption. (It should work and it feels better than having "random" text on the same slide)

[Lulliter]

For my purposes creating cross-referenceable figures is too much work (this is a class demonstrating several ggplot graphs in a row), but I think patchwork can be a good compromise for now.

---
title: ""
format: revealjs
---

## This is what I wanted but can't get rid of `cat(...)`
```{r}
#| echo: true
#| eval: true
#| output-location: slide

library(dplyr)
library(ggplot2)

starwars %>% 
  filter(homeworld == c("Alderaan","Tatooine" )) %>% 
  ggplot( aes(x = height,fill = homeworld))+
  geom_density(alpha = 0.5)  

cat("\nHere you see how the distribution is not normal\n")
```

## Maybe `patchwork` is a good workaround for now
```{r}
#| echo: true
#| eval: true
#| output-location: slide

library(dplyr)
library(ggplot2)
library(patchwork)

plot <- starwars %>% 
  filter(homeworld == c("Alderaan","Tatooine" )) %>% 
  ggplot( aes(x = height,fill = homeworld))+
  geom_density(alpha = 0.5)  

plot + plot_annotation(title = "Here you see how the distribution is not normal" )
```   

[mcanouil]

Too much work to add #| fig-cap: "Your caption/comment"?

[Lulliter]

right! that works too