docs: add vignette

.Rbuildignore

@@ -8,3 +8,4 @@
 ^pkgdown$
 ^man/universe_query\.Rd$
 ^\.lintr$
+^vignettes/articles$

DESCRIPTION

@@ -22,3 +22,4 @@ Suggests:
     httptest2,
     testthat (>= 3.0.0)
 Config/testthat/edition: 3
+Config/Needs/website: rmarkdown

vignettes/.gitignore

@@ -0,0 +1,2 @@
+*.html
+*.R

vignettes/articles/starchart.Rmd

@@ -0,0 +1,47 @@
+---
+title: "starchart"
+---
+
+```{r, include = FALSE}
+knitr::opts_chunk$set(
+  collapse = TRUE,
+  comment = "#>"
+)
+```
+
+The goal of starchart is to access the R-universe API.
+
+## All packages in an universe
+
+```{r example}
+library(starchart)
+universe_ls("jeroen")
+```
+
+## Info on all packages in an universe
+
+```{r}
+universe_packages("jeroen", limit = 1) |>
+  str(max.level = 2)
+```
+
+## Info on a single package in an universe
+
+```{r}
+universe_package("jeroen", package = "curl") |>
+  str(max.level = 2)
+```
+
+## Search within a single universe
+
+```{r}
+universe_search("ropensci", query = 'needs:httr2', limit = 1) |>
+  str(max.level = 2)
+```
+
+## Search among all universes
+
+```{r}
+global_search(query = '"weather data"', limit = 1) |>
+  str(max.level = 2)
+```