Need better docs/samples for access items in a tuple

[billti]

Copilot struggled to generate code that accessed the elements of a tuple. Looking at our docs and samples we have very little covering this (basically one sentance on https://learn.microsoft.com/en-us/azure/quantum/user-guide/language/statements/variabledeclarationsandreassignments). We should add more content explicitly covering this.

[billti]

@DmitryVasilevsky can you add/expand on the language samples to include this.