Update user wiki page of script generator to match UI

[LowriJenkins]

There have been some updates to the script generator, including a link to the user wiki page of script generator. The wiki page should be updated to reflect this. As well as this the numbered lists should be updated so that they correctly refer to the button labeled with that number.

https://github.com/ISISComputingGroup/ibex_user_manual/wiki/Using-the-Script-Generator

Acceptence criteria

Ensure links to this page are not broken, and images on the page work.
The images should reflect the current layout of the script generator, and the labels and there bullet points should match.
These changes assume that #5616 will have been merged by this point, and thus images should include the global parameter text boxes.