Merging docs

These instructions are for ggplot2 collaborators who can make changes to the main repo. They detail the steps to take when someone submits a pull request for documentation changes.

1. Check the commit for correctness and style. If the commit touches existing poorly-formatted code, that code should be bought up to spec. If style or change is incorrect, respond to the requester with a polite request for changes.

2. Follow the pull request instructions to merge change into develop branch.

3. Run document() to ensure .Rd files are updated, and add entry to NEWS. If significant change, add a bullet point under DOCUMENTATION heading, otherwise, add requestors name to list of people who've made smaller changes. Check news with show_news()

4. Commit and push.