Releases for Gesso

Major changes:
adds create_attribute function for Pattern Lab
improved documentation
adds icon component that uses a SVG sprite
lints markdown files
updates pattern lab version
updates breakpoint design token names
updates font size and spacing key naming
dependency updates + Prettier plugin swap
shares design tokens with JS
relaxes some linting rules
adds captioned-image component
removes vertical-spacing mixin that was being tested in 3.x dev version
fixed contextual links in blocks with no title