Updated docstrings to inform users that ODE solution may be slow.

[dmburt]

Updated docstrings for init.py and pymc.ode.DifferentialEquation

Docstrings now provide additional information that ODE solution performance may be slow and provide a link to the sunode library (based on PyMC).

@reshamas
#DataUmbrellaPyMCSprint

[dmburt]

Worked on solution with @azulcou

[codecov]

Codecov Report

Merging #5965 (6f64540) into main (f617180) will decrease coverage by 0.14%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #5965      +/-   ##
==========================================
- Coverage   89.52%   89.38%   -0.15%     
==========================================
  Files          73       73              
  Lines       13271    13249      -22     
==========================================
- Hits        11881    11842      -39     
- Misses       1390     1407      +17     

Impacted Files	Coverage Δ
pymc/ode/__init__.py	100.00% <ø> (ø)
pymc/ode/ode.py	85.85% <ø> (ø)
pymc/__init__.py	68.42% <0.00%> (-31.58%)	⬇️
pymc/data.py	81.48% <0.00%> (-0.16%)	⬇️
pymc/distributions/continuous.py	97.89% <0.00%> (-0.10%)	⬇️
pymc/distributions/logprob.py	97.72% <0.00%> (ø)
pymc/distributions/discrete.py	99.21% <0.00%> (ø)
pymc/step_methods/mlda.py	96.38% <0.00%> (+0.01%)	⬆️
pymc/model_graph.py	93.70% <0.00%> (+0.10%)	⬆️
pymc/model.py	88.20% <0.00%> (+0.14%)	⬆️

[michaelosthege]

Thanks @dmburt and @azulcou!