Use subplots() instead of axes_grid in suitable examples.

[anntzer]

PR Summary

These are examples where subplots() is just as good as axes_grid to set up the axes.

In simple_annotate01, the subplots order was swapped to allow the
"connectionstyle=arc3" label to overflow without being cut off.

For reference, compare

https://matplotlib.org/gallery/userdemo/annotate_explain.html#sphx-glr-gallery-userdemo-annotate-explain-py
https://matplotlib.org/gallery/userdemo/simple_annotate01.html#sphx-glr-gallery-userdemo-simple-annotate01-py
https://matplotlib.org/gallery/userdemo/connectionstyle_demo.html#sphx-glr-gallery-userdemo-connectionstyle-demo-py

and

https://955-7439715-gh.circle-artifacts.com/0/home/circleci/project/doc/build/html/gallery/userdemo/annotate_explain.html#sphx-glr-gallery-userdemo-annotate-explain-py
https://955-7439715-gh.circle-artifacts.com/0/home/circleci/project/doc/build/html/gallery/userdemo/simple_annotate01.html#sphx-glr-gallery-userdemo-simple-annotate01-py
https://955-7439715-gh.circle-artifacts.com/0/home/circleci/project/doc/build/html/gallery/userdemo/connectionstyle_demo.html#sphx-glr-gallery-userdemo-connectionstyle-demo-py

PR Checklist

• Has Pytest style unit tests
• Code is PEP 8 compliant
• New features are documented, with examples if plot related
• Documentation is sphinx and numpydoc compliant
• Added an entry to doc/users/next_whats_new/ if major new feature (follow instructions in README.rst there)
• Documented in doc/api/api_changes.rst if API changed in a backward-incompatible way

[dstansby]

Big 👍 for this

[jklymak]

I don't think either comment is a blocker, and I'm all for reducing AxesGrid in the docs, but these examples don't look like the old ones. Is that OK? I think I'm OK w/ it, but wanted to point it out.

[jklymak]

Did you change the shape on purpose? I don't really mind, but the original was 1x4...

[anntzer]

Then you'd need to set a figsize (otherwise the subplots are really small), and it just works as well without it after reshaping to (2, 2). Basically, trying to concentrate the example on the relevant points.

(the connectionstyle example does set the figsize because I don't think it can really be made to work nicely without it).

[jklymak]

Again, I don't mind it, but this one is pretty different from the old version.

[anntzer]

The previous example had a bunch of empty, useless subplots.
The reason for reordering the subplots is explained above, but again it's just so that "connectionstyle=arc3" doesn't get overwritten by the next subplot.

[jklymak]

Thanks @anntzer