Enhancements in the Color Palette REST API example

I've noted a few topics where the example for the use of REST API in Qt and with the Qt HTTP Server can be improved:

• the example on the server side (https://doc.qt.io/qt-6/qthttpserver-colorpalette-example.html) does not contain a reference to the client-side implementation (https://doc.qt.io/qt-6/qtdoc-demos-colorpaletteclient-example.html)
• Both examples use the word "RESTful" too often which throws them out of search on Google if people are asking "qt REST example" or similar. Especially the title should have REST and not RESTful, even though RESTful would be more correct.