Fortigate doc / Add working example + GUI guide (user feedback)

[alexane-bougeardbebin-sekoia]

User feedback on Fortigate doc:

Survey: Not useful > Add a working example > "So confusing. Please add a GUI guide as well. Do not use "..." in code blocks, mention in explanation if there are more to add"

Could you please have a look? I am available if you need any help to enhance this doc.