Wrong argument references in aggregate function help

[qgib]

Author Name: Harrissou Santanna (@DelazJ)
Original Redmine Issue: 18683
Affected QGIS version: 3.1(master)
Redmine category:expressions

---

In the expression builder, select the aggregate function, the examples at the bottom of the help section use an expression:= argument that is not described in the argument section and i feel like there's a misuse in the examples between aggregate, calculation and expression arguments

I think this is true back to (at least) 2.18

[alexbruy]

Already fixed in master. Please reopen if necessary.