Add some details on "javascript" page

This PR tries to help newcomers, adding some information on "getting-started => javascript"

Changes:

• minor typos
• group jQuery stuff & add details of use
• add details about Data attributes usage (plus data-bs-config)
• explain the difference getInstance & getOrCreateInstance methods
• add async usage example in addition with dispose method
• add shared methods & properties

Needs:

• a native speaker to proofread the changes & additions

Preview : https://deploy-preview-36363--twbs-bootstrap.netlify.app/docs/5.2/getting-started/javascript/