Improve subprocess docs

[visr]

Fixes #1638

[visr]

The print(result.stderr) can get very long for long simulations, since each progress bar update gets captured. I haven't yet looked into options to understand the escape sequences, or disabling the progress bar. We could always do that later on, for now this is a clear improvement.

┌ Info: Starting a Ribasim simulation.
│   cli.ribasim_version = "2024.9.0"
│   starttime = 2020-01-01T00:00:00
└   endtime = 2021-01-01T00:00:00
Simulating   0%|█                                       |  ETA: N/A
Simulating   3%|██                                      |  ETA: 0:06:05
Simulating  27%|███████████                             |  ETA: 0:00:26
Simulating  55%|██████████████████████                  |  ETA: 0:00:08
Simulating  82%|█████████████████████████████████       |  ETA: 0:00:02
Simulating 100%|████████████████████████████████████████| Time: 0:00:09
┌ Info: Convergence bottlenecks in descending order of severity:
│   Basin #1 = 8.381532618938586e-5
└   Basin #3 = 7.804332800509216e-5
[ Info: The model finished successfully