[proper] documentation

[siva2204]

• need proper docmentation, can use docusaurus
• add following content
  • dauth intro
  • oauth intro
  • oidc
  • supported flow (authorization code grant flow, authorization code grant flow with pkce)
  • dauth routes and http request boilerplate in more than 2 languages
    • authorize route
    • token route
    • resource route
  • other packages around dauth like flutter_dauth, passport dauth
  • example implementation of dauth in different languages