Update functions.md (#48356)

According to the documentation at https://docs.julialang.org/en/v1/base/collections/#Base.get, the example here of a no argument function does not appear to implement a time delay as suggested in this doc.

Author: sepesi

doc/src/manual/functions.md

@@ -348,7 +348,7 @@ get(()->time(), dict, key)
 ```
 
 The call to [`time`](@ref) is delayed by wrapping it in a 0-argument anonymous function
-that is called only when the requested key is absent from `dict`.
+that is called only if the requested key is absent from `dict`.
 
 ## Tuples