feat: add a11y plugin and fix a11y violations

[anapaulalemos]

• Installed the a11y pluign
• Fixed all violations found
• Updated tags to have the colours defined on figma
• Updated colour palette
• Updated documentation about colours
• Generate a brand new package

To test

npm i
npm run storybook

Go to the accessibility tab:

And check if any component, template or pattern has any violation