Update CONTRIBUTING.md document across our repositories

[timbru31]

Description

We have updated our CONTRIBUTING.md document in apache/cordova-contribute#37. Those changes need to be added to our other repositories, too:

Implementation Progress

Platforms

• cordova-android
• cordova-browser
• cordova-electron
• cordova-ios
• cordova-osx
• cordova-test-platform
• cordova-windows

Plugins

• cordova-plugin-battery-status
• cordova-plugin-camera
• cordova-plugin-device
• cordova-plugin-dialogs
• cordova-plugin-file
• cordova-plugin-geolocation
• cordova-plugin-inappbrowser
• cordova-plugin-media
• cordova-plugin-media-capture
• cordova-plugin-network-information
• cordova-plugin-screen-orientation
• cordova-plugin-splashscreen
• cordova-plugin-statusbar
• cordova-plugin-vibration
• cordova-plugin-whitelist
• cordova-plugin-wkwebview-engine

Tooling

• cordova-cli
• cordova-coho
• cordova-common
• cordova-create
• cordova-docs
• cordova-fetch
• cordova-js
• cordova-lib
• cordova-mobile-spec
• cordova-node-xcode
• cordova-paramedic
• cordova-plugin-test-framework
• cordova-plugman
• cordova-serve

Misc

• cordova
• cordova-app-hello-world

Excluded:

• cordova-status

and any unused, outdated, or deprecated repos.