updated README

README.md

@@ -1,17 +1,35 @@
 # swirl
 
 [![Build Status](https://travis-ci.org/swirldev/swirl.png?branch=master)](https://travis-ci.org/swirldev/swirl)
+[![CRAN version](http://www.r-pkg.org/badges/version/swirl?color=3399ff)](https://cran.r-project.org/web/packages/swirl/index.html)
 [![Downloads](http://cranlogs.r-pkg.org/badges/swirl?color=3399ff)](http://cran-logs.rstudio.com/)
 
 ### [http://swirlstats.com](http://swirlstats.com)
 
-swirl is a platform for learning (and teaching) statistics and R simultaneously and interactively. It presents a choice of course lessons and interactively tutors a user through them. A user may be asked to watch a video, to answer a multiple-choice or fill-in-the-blanks question, or to enter a command in the R console precisely as if he or she were using R in practice. Emphasis is on the last, interacting with the R console. User responses are tested for correctness and hints are given if appropriate. Progress is automatically saved so that a user may quit at any time and later resume without losing work.
+swirl is a platform for learning (and teaching) statistics and R simultaneously 
+and interactively. It presents a choice of course lessons and interactively 
+tutors a student through them. A student may be asked to watch a video, to answer a 
+multiple-choice or fill-in-the-blanks question, or to enter a command in the R 
+console precisely as if he or she were using R in practice. Emphasis is on the 
+last, interacting with the R console. User responses are tested for correctness 
+and hints are given if appropriate. Progress is automatically saved so that a 
+user may quit at any time and later resume without losing work.
 
-swirl leans heavily on exercising a student's use of the R console. A callback mechanism, suggested and first demonstrated for the purpose by Hadley Wickham, is used to capture student input and to provide immediate feedback relevant to the course material at hand.
+swirl leans heavily on exercising a student's use of the R console. A callback 
+mechanism, suggested and first demonstrated for the purpose by Hadley Wickham, 
+is used to capture student input and to provide immediate feedback relevant to 
+the course material at hand.
 
-[swirlify](https://github.com/swirldev/swirlify) is a separate R package that provides a comprehensive toolbox for swirl instructors. Content is authored in [YAML](http://en.wikipedia.org/wiki/YAML) using the handy tools described on the [instructors page](http://swirlstats.com/instructors.html) of our website.
+[swirlify](https://github.com/swirldev/swirlify) is a separate R package that 
+provides a comprehensive toolbox for swirl instructors. Content is authored in 
+[YAML](http://en.wikipedia.org/wiki/YAML) using the handy tools described on 
+the [instructors page](http://swirlstats.com/instructors.html) of our website.
 
-The program is initiated with `swirl()`. Functions which control swirl's behavior include `bye()` to quit, `skip()` to skip a question, `main()` to return to the main menu, `play()` to allow experimentation in the R console without interference from swirl, `nxt()` to resume interacting with swirl, and `info()` to display a help menu.
+The program is initiated with `swirl()`. Functions which control swirl's 
+behavior include `bye()` to quit, `skip()` to skip a question, `main()` to 
+return to the main menu, `play()` to allow experimentation in the R console 
+without interference from swirl, `nxt()` to resume interacting with swirl, and 
+`info()` to display a help menu.
 
 
 ## Installing swirl (from CRAN)
@@ -24,25 +42,34 @@ library(swirl)
 swirl()
 ```
 
-As we continue adding new features and content, we will make new versions available on CRAN as appropriate (every 1-2 months, most likely).
+As we continue adding new features and content, we will make new versions 
+available on CRAN as appropriate (every 1-2 months, most likely).
 
 ## Installing the latest development version (from GitHub)
 
-To access the most recent features and content, you can install and run the development version of swirl using the [devtools](https://github.com/hadley/devtools) package:
+To access the most recent features and content, you can install and run the 
+development version of swirl using the [devtools](https://github.com/hadley/devtools) package:
 
 ```
 install.packages("devtools")
-devtools::install_github("swirldev/swirl")
+devtools::install_github("swirldev/swirl", ref = "dev")
 library(swirl)
 swirl()
 ```
 
 ## Contributing to swirl's development
 
-If you'd like to get involved, please fork this repository and submit a pull request with your proposed changes. We're happy to chat if you have any questions about the source code.
+If you'd like to get involved, please fork this repository and submit a pull 
+request with your proposed changes. We're happy to chat if you have any 
+questions about the source code.
 
 ## Using swirl in the classroom
 
-Instructors around the world are using swirl in their classrooms. We think this is awesome. If you're an instructor, please feel free to do the same -- free of charge. While your students may be paying to take your course or attend your institution, we simply ask that you don't charge people *directly* for the use of our software or instructional content.
+Instructors around the world are using swirl in their classrooms. We think this
+is awesome. If you're an instructor, please feel free to do the same -- free of
+charge. While your students may be paying to take your course or attend your 
+institution, we simply ask that you don't charge people *directly* for the use 
+of our software or instructional content.
 
-If you are not sure about a particular use case, don't hesitate to send us an email at [email protected].
+If you are not sure about a particular use case, don't hesitate to send us an 
+email at [email protected].