Clarify the "modify a map" in hash-map's doc.

[atototenten]

"add or remove keys" is already mentioned ,but what about the "value" ?

[lrhn]

The text is: "Do not modify a map (add or remove keys) ".
Changing values are not mentioned because it doesn't count as modifying the (structure of the) map.

Could be more explicit about that, or be clearer that it's the map structure (the set of keys) that matter when iterating.