Tile Usage Policy: clarify X tiles per Y time

[jidanni]

https://operations.osmfoundation.org/policies/tiles/ says

In particular, downloading an area of over 250 tiles at zoom level 13 or higher for offline or later usage is forbidden.

Well OK, but it should say "at a time", or "at one time", and if that "time" is "within the same 30 minutes, hour, day, month or lifetime".

[GurminderSingh7]

i want to contribute, can you please assign this to me