Update the Qt Design Studio on MCUs doc subset

Update the Qt Design Studio on MCUs documentation subset.

Check and discuss whether there's a possibility to continue the work on the following open tasks within the QDS 4.7/ Qt for MCUs 2.9 time frame:

• Running a ready-made MCU project in QDS (QDS-9289)
• Running a QDS application on the desktop QUL Simulator (QDS-9290)
• Running a QDS application on the target MCU (QDS-9291)

Go through the current Qt Design Studio on MCUs documentation subset (https://doc.qt.io/qtdesignstudio/studio-on-mcus.html) with the key QDS/ Qt for MCUs developers, list the modification needs, and update the pages accordingly.