DOC: Substitute example in DataFrame.to_markdown docstring (#42126)
- [ ] closes #42126 
- [ ] tests added / passed
- [ ] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them
- [ ] whatsnew entry

Nice, thanks @neinkeinkaffee ! Did you try building these pages locally to check that they show up fine? If so, could you post a screenshot?

see [here](https://pandas.pydata.org/pandas-docs/stable/development/contributing.html#building-the-documentation) for how to build the docs locally, you'll probably want to use the `--single` option with `pandas.DataFrame.to_markdown` Sure! This is how they look like:

<img width="697" alt="Screenshot 2021-06-20 at 15 27 52" src="https://user-images.githubusercontent.com/1748562/122677903-496fb500-d1dc-11eb-89f6-679b1841d0c5.png">
<img width="704" alt="Screenshot 2021-06-20 at 15 28 12" src="https://user-images.githubusercontent.com/1748562/122677905-4aa0e200-d1dc-11eb-8346-4d80145a5f16.png">


 Thanks - From the first screenshot you posted (DataFrame.to_markdown), it looks like the Series example is still the one being substituted into the docstring :thinking:  OMG, you're right, weird, I could swear it was alright when I checked earlier! Will check what happened there Here it is one more time:

<img width="672" alt="Screenshot 2021-06-20 at 17 20 14" src="https://user-images.githubusercontent.com/1748562/122681366-d0785980-d1eb-11eb-9cb4-84bf21236b9d.png">
 we could also add `to_markdown` to `user_guide/io/rst`. It recently had some output methods added, but I didn't even know this one existed.  Good idea - @neinkeinkaffee if you wanted to do that (in a separate PR) it'd be welcome, else we can open it as an issue for others to take

CI failures here are probably unrelated, if you fetch and merge upstream/master once CI is fixed they'll probably be fine @MarcoGorelli Sure, I'll add it to userguide/io.rst and submit a separate PR for that.

Regarding the failing CI check of this one, do you mean I should just merge my branch with master again and that might fix it? Yeah, that's right - latest PRs seem to be mostly green, so if you fetch and merge upstream/master now that might be enough Updated with the most recent commits from master, hopefully that'll make the checks go green. I'll work on updating the io.rst on a separate branch. Actually, having a second look at io.rst I see that the documentation for each of the read and write methods is quite extensive there, containing lots of tips and tricks. Not sure if I can come up with something like that for `to_markdown` on the spot, it looks like a bigger project to be honest :) No worries, I can open it up as an issue and someone else will take it! Thanks for your help on this one! @simonjayhawkins I've seen some recent docs PRs being tagged as 1.3, is that an OK milestone for this one too? ![](https://i.fluffy.cc/MKjDMmwXxZlqRTwnn070gVqZ8Rwh6d3p.gif)