Document how-to setup renovate on packages

Document the following in a markdown under Big Bang's documentation:

• What is renovate and why we are using it
• How is the renovate automated run setup
  • where the cron/pipeline is
  • where the Iron Bank and Repo1 credentials are
  • Scope of the folders/files it will search
  • Where to update frequency of job
  • Special permissions required to access configuration (if any)
  • Where to update renovate bot version
• How a typical package would setup renovate.json for version/SHA updates
• How a package owner would test renovate without having to wait for the bot