[BUG]: Fix in documentation

[vectronic]

Describe the bug
In the code example here:

https://github.com/bbc/tams/#flow-and-media-timelines

For the "timerange/ts_offset approach" pseudo-code it says:

object_ts = to_timestamp(ts)          # `4:0` for `ts = 4.0sec`
offset_object_ts = object_ts + ts_offset    # `4:0 + -0:700000000 = 3:300000000` (in Flow timeline)
if (offset_object_ts < timerange.start or
      offset_object_ts >= timerange.end):  # `3:300000000 is less than 3:500000000`
    discard_grain()                  # So this grain is discarded
else:
    keep_grain()                     # The first grain to be retained will have `object_ts = 4.2`
                                     # (and `offset_object_ts = 3:500000000 or 3.5sec)`

This doesn't match the diagram above in which object Y05 has a tr_offset of -0.8

Expected behavior

To match the diagram the pseudo-code should say:

`object_ts = to_timestamp(ts)          # `4:0` for `ts = 4.0sec`
offset_object_ts = object_ts + ts_offset    # `4:0 + -0:800000000 = 3:200000000` (in Flow timeline)
if (offset_object_ts < timerange.start or
      offset_object_ts >= timerange.end):  # `3:200000000 is less than 3:500000000`
    discard_grain()                  # So this grain is discarded
else:
    keep_grain()                     # The first grain to be retained will have `object_ts = 4.3`
                                     # (and `offset_object_ts = 3:500000000 or 3.5sec)`

[j616]

Thank you for your report. I've created #218 to fix this.