Improve API docs for HTTP client authentication.
Improve API docs for HTTP client authentication.

Fixes #16489

ndm2/cakephp,cakephp/cakephp,ndm2/cakephp,cakephp/cakephp,ndm2/cakephp,cakephp/cakephp,ndm2/cakephp,cakephp/cakephp