PR Summary

Closes #21441

import matplotlib.pyplot as plt

fig = plt.figure()

pos1 = [0.1, 0.1, 0.3, 0.8]
pos2 = [0.5, 0.1, 0.4, 0.6]

ax1 = plt.axes(position = pos1)
ax1.plot([0,1], [0, 1], color = 'r', linewidth = 3)

ax2 = plt.axes(position = pos2)
ax2.plot([1, 0], [0, 1], color = 'b', linestyle = '--')

is documented to work, but position is silently ignored. position is just redundant with rect, so go ahead and check for position if rect is None.

PR Checklist

• Has pytest style unit tests (and pytest passes).
• Is Flake 8 compliant (run flake8 on changed files to check).
• New features are documented, with examples if plot related.
• Documentation is sphinx and numpydoc compliant (the docs should build without error).
• Conforms to Matplotlib style conventions (install flake8-docstrings and run flake8 --docstring-convention=all).
• New features have an entry in doc/users/next_whats_new/ (follow instructions in README.rst there).
• API changes documented in doc/api/next_api_changes/ (follow instructions in README.rst there).