add very quick intro vignette

Author: timelyportfolio

.gitignore

@@ -2,3 +2,4 @@
 .Rhistory
 .RData
 .Ruserdata
+inst/doc

DESCRIPTION

@@ -19,7 +19,9 @@ Authors@R: c(
 Maintainer: Kent Russell <[email protected]>
 Description: Make it easy to use 'react' in R with helper
               dependency functions, embedded 'Babel' transpiler,
-              and examples.
+              and examples.  Please note the separate 'react'
+              [BSD license](https://github.com/facebook/react/blob/master/LICENSE)
+              when using 'reactR' and 'react' in your projects.
 URL: https://github.com/timelyportfolio/reactR
 BugReports: https://github.com/timelyportfolio/reactR/issues
 License: BSD_3_clause + file LICENSE
@@ -30,5 +32,7 @@ Suggests:
     htmlwidgets (>= 0.6.0),
     rmarkdown,
     shiny,
-    V8
+    V8,
+    knitr
 RoxygenNote: 5.0.1
+VignetteBuilder: knitr

vignettes/intro_reactR.Rmd

@@ -0,0 +1,55 @@
+---
+title: "Intro to reactR"
+author: "Kent Russell"
+date: "`r Sys.Date()`"
+output: rmarkdown::html_vignette
+vignette: >
+  %\VignetteIndexEntry{Intro to reactR}
+  %\VignetteEngine{knitr::rmarkdown}
+  %\VignetteEncoding{UTF-8}
+---
+
+## Why reactR?
+
+[`react`](https://facebook.github.io/react/) has become incredibly popular, and the ecosystem around `react` is robust.  `reactR` aims to allow `R` users to more easily incorporate `react` and `JSX`.
+
+## Install
+
+```
+install.packages("reactR")
+
+# for the latest development version
+#  install from Github
+# devtools::install_github("timelyportfolio/reactR")
+```
+
+## Quick Example
+
+Let's use `react` to render a simple `h1` HTML element below.
+
+<div id="react-heading-here"></div>
+
+```{r}
+library(reactR)
+library(htmltools)
+
+attachDependencies(
+  tags$script(
+  "
+    ReactDOM.render(
+      React.createElement(
+        'h1',
+        null,
+        'Powered by React'
+      ),
+      document.getElementById('react-heading-here')
+    )
+  "
+  ),
+  html_dependency_react()
+)
+```
+
+## Using JSX
+
+[`JSX`](https://facebook.github.io/react/docs/jsx-in-depth.html) helps ease some of the burden caused by `React.createElement`.  `reactR` provides a `babel_transform()` function to use `JSX`.  Hopefully, in the future, we can convince RStudio to modify `htmltools` to work directly with `JSX` (see [issue](https://github.com/rstudio/htmltools/pull/72)).