Configuration script: user info and end session endpoint

[shawnhankim]

Background:

• The configure.sh script currently supports to complete the following configuration if an IdP supports OpenID Connect Discovery (usually at the URI /.well-known/openid-configuration).
  • Obtain the URL for jwks_uri or download the JWK file to your NGINX Plus instance
  • Obtain the URL for the authorization endpoint
  • Obtain the URL for the token endpoint
• NGINX Plus OIDC additionally exposed the endpoints of user information and logout in the PR. Hence they need to be configured by using configure.sh.

Acceptance Criteria:

• Supports configure.sh to additionally complete the following configuration.
  • Obtain the URL for the user information endpoint of IdP.
  • Obtain the URL for the end session endpoint of IdP.
• Update README.md.

[shawnhankim]

Per discussion with @route443 : I close this PR because I have consolidated this PR into https://github.com/nginxinc/nginx-openid-connect/issues/55. Thanks @route443 for your time. The doc PR will be separately opened. 👍