WEB: add mastodon links
- [x] closes #52914
- [x] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [ ] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [x] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.
- [ ] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

Sidebar:
![Screenshot from 2023-04-26 22-24-40](https://user-images.githubusercontent.com/1196901/234743959-187edc47-4263-4072-9862-e0c1c651535b.png)

Footer:
![image](https://user-images.githubusercontent.com/1196901/234743877-fdad91bd-c8dc-4b78-a908-dd38125f4c48.png)

/preview No preview found for PR #52954. Did the docs build complete? > /preview

There was a problem with the GitHub token and previews of the last couple of days aren't available. It should be fixed now, the preview for this PR should be available when the CI rerun finishes. @datapythonista it _could_ be, but I had some ideas around ordering:

In the api docs, the Twitter & mastodon links are currently in a different order than I put them on the web site. And the Twitter image is a (imo) distractingly bright blue — I was toying with unifying the order and appearance of the links in the api docs.

But it has been fairly difficult to build them!

Anyway, you can merge this if you like - I think it works OK — but I hadn’t just finished all my due diligence. Sure, no rush, I was just wondering if there was a reason.

If it makes your life easier, we can also merge this now and you can work on those in a separate PR. But surely fine to continue here if you prefer. /preview Website preview of this PR available at: https://pandas.pydata.org/preview/52954/ Yeah you're right - this can be done incrementally - the current state is fine. I ran into another issue building the api docs, but I was able to confirm at least that the mastodon icon showed up. So this is good from my end. Will mark as ready. Thanks @mikix 