Add demos

[VladimirAlexiev]

It will be very useful and attractive if
https://yasgui.matdata.eu/ can include demos.

• Should not be extremely hard by using a Workspace and SPARQL queries saved on Github
• this plugin already has a demo page: https://github.com/Matdata-eu/yasgui-graph-plugin/tree/main/demo, I mean something like that

[MathiasVDA]

Yes, I also had something like that in my mind but haven't gotten around to it yet. Good idea Vladimir

[MathiasVDA]

Is now implemented on https://matgui.matdata.eu

You can copy the demo workspace to other implementations if you like. I've created about 100 queries using different endpoints, return types and techniques