Doc: Add missing files required for remote CDB debugging

https://doc.qt.io/qtcreator/creator-debugger-operating-modes.html#using-cdb makes it sound like you only need to copy qtcreatorcdbext.dll to the remote machine.

However, you need to copy its dependencies too, or else the remote debugger will fail to launch with the error, "the specified module could not be found".

As of Qt Creator 7.0.2, the following 3 files must be copied:

• python38.dll
• python38.zip
• qtcreatorcdbext.dll