bpmodels v0.3.0

Website

• The website has been updated to use bootstrap 5. This means it has a slightly
  new look.
• Exported functions under "references" have been grouped into topics.

Vignettes

• A new vignette has been added to compile a bibliography of papers that
  apply branching processes to infectious disease epidemiology.
• The "quickstart" section of the README has been moved to the "Getting started"
  section of the website.
• The README now only provides a quick description of the core functions in the
  package and users are referred to the website for a quick start.

README

• The README no longer has a quickstart section as it has been moved to the
  website. This is to give the README a minimalistic look.