Extending roxygen vignette should mention how to add your extension to your workflow

[hughjonesd]

I've been playing with a small package to write doctests in roxygen. The "extending roxygen" vignette has been very helpful. One thing I missed was some guidance on how to add a new roclet to your workflow.

Something like this:

## Adding a roclet to your workflow

To use a roclet when developing a package, call

    ```r
    roxygen2::roxygenize(roclets = "yourPackage::roclet")
    ```

where `yourPackage::roclet` is the function which creates the roclet.

You can also add the roclet to the target package DESCRIPTION file, like:

    ```r
    Roxygen: list(roclets = c("collate", "rd", "namespace", "yourPackage::roclet")) 
    ```

You can also optionally add your roclet package to the target package as a Suggests dependency:

    ```r
    usethis::use_dev_package("yourPackage", type = "Suggests", remote = "yourGithubID/yourPackage")
    ```

You don't have to do this, but it will help other developers working on the target package.

I can provide a PR if you want.

[moodymudskipper]

I would like to see the examples from the vignette implemented in an actual package. While I could define custom tags, I couldn't define custom roclets so far, even with the above.

[hadley]

A PR would be great if you're still interested.

[hughjonesd]

First draft...