[docs] Add template for plugin READMEs

[jlengstorf]

It would be helpful to have a standard format for plugin READMEs that covers standard information:

• How to install
• Available options (if any)
• Example(s) of usage (or before-and-after examples of data when the plugin is enabled)
• How to run tests
• How to develop locally
• How to contribute

If a CLI add-on for generating plugins comes to be, this template could easily be generated with the plugin's actual information, but that's down the road a bit.

Other things that still need to be figured out:

• Where do we keep this template? (e.g. its own repo, in the docs somewhere)
• Should we/how do we update existing plugins to use the updated format?
• Does this template change significantly depending on whether the repo is a source, transformer, or general plugin?

[KyleAMathews]

This looks great!

Perhaps we could also add "When do I use this" with very approachable user stories.

@kentcdodds has a README template https://github.com/kentcdodds/generator-kcd-oss/blob/master/generators/app/templates/README.md

On where to store this — we have a poorly documented setup for generating new packages for this repo https://github.com/gatsbyjs/gatsby/blob/master/plop-templates/package/README.md.hbs

We should move that into the gatsby-cli and make it super awesome.

[calcsam]

cc @ajayns

[ajayns]

If a CLI add-on for generating plugins comes to be, this template could easily be generated with the plugin's actual information

This sounds very interesting, could save a lot of time on getting started and will also improve consistency in plugins

[shannonbux]

@jlengstorf I just referenced this issue in a PR where I've included a plugin READme template. Open to ideas of a better place to put the template!

[shannonbux]

closed by #6489