docs: example - avoid duplicate metrics with same name and labels

[corporate-gadfly]

No description provided.

[corporate-gadfly]

Perhaps you may know something about it, but when bumping from 0.12.1 to 0.12.2, a query that was returning duplicate rows was giving errors:

ts=2023-09-16T19:38:51.958Z caller=klog.go:124 level=error func=Errorf msg="Error gathering metrics:
....
gauge:{value:5.24288e+08}} was collected before with the same name and label values

So, I introduced an element in the WHERE clause to de-duplicate the returned rows.

[burningalchemist]

Hey @corporate-gadfly, this example was contributed before. I don't have access to Azure to check it. So, thanks for checks and improvements. 🙂👍

[corporate-gadfly]

@burningalchemist : No worries. I'm the original submitter of the example.