docs: Supplements the openid-connect configuration doc

[wensenz]

This configuration is used when token introspection endpoints require additional parameters

Description

Supplements the openid-connect configuration document

Checklist

• I have explained the need for this PR and the problem it solves
• I have explained the changes or the new features added to this PR
• I have added tests corresponding to this change
• I have updated the documentation to reflect this change
• I have verified that this change is backward compatible (If not, please discuss on the APISIX mailing list first)

[kayx23]

Will need to add this to the schema of apisix/plugins/openid-connect.lua as well and update the English doc.

Preferably add a test case.

[wensenz]

Will need to add this to the schema of apisix/plugins/openid-connect.lua as well and update the English doc.

Preferably add a test case.

done..

[kayx23]

Will need to add this to the schema of apisix/plugins/openid-connect.lua as well and update the English doc.
Preferably add a test case.

done..

schema is not updated? in apisix/plugins/openid-connect.lua

[wensenz]

Will need to add this to the schema of apisix/plugins/openid-connect.lua as well and update the English doc.
Preferably add a test case.

done..

schema is not updated? in apisix/plugins/openid-connect.lua

This is not necessary. In apisix/plugins/openid-connect.lua:413 -> lua-resty-openidc/lib/resty/openidc.lua:1740, the introspection_params is already supported.

[wensenz]

Configure the plugin like this, it works

"plugins": {
    "openid-connect": {
      "_meta": {
        "disable": false
      },
      "bearer_only": true,
      "client_id": "your client_id",
      "client_secret": "your client_secret",
      "discovery": "http://your host/.well-known/openid-configuration",
      "introspection_endpoint": "http://your host/api/login/oauth/introspect",
      "introspection_endpoint_auth_method": "client_secret_basic",
      "introspection_params": {
        "token_type_hint": "access_token"
      }
    }
  },

[kayx23]

Yes it will work; however introspection_params should still be added to the plugin schema. The other parameters supported by lua-resty-openidc and APISIX were also added to schema in the same way. @shreemaan-abhishek thoughts?