docs: remove recommonmark

[henryiii]

I think this slipped in from boost-histogram, and is unused. CC readthedocs/recommonmark#221

[sourcery-ai]

Sourcery Code Quality Report

✅  Merging this PR will increase code quality in the affected files by 1.56%.

Quality metrics	Before	After	Change
Complexity	0.00 ⭐	0.00 ⭐	0.00
Method Length	83.00 🙂	82.00 🙂	-1.00 👍
Working memory	14.00 😞	13.00 😞	-1.00 👍
Quality	64.80% 🙂	66.36% 🙂	1.56% 👍

Other metrics	Before	After	Change
Lines	37	36	-1

Changed files	Quality Before	Quality After	Quality Change
setup.py	64.80% 🙂	66.36% 🙂	1.56% 👍

Here are some functions in these files that still need a tune-up:

File	Function	Complexity	Length	Working Memory	Quality	Recommendation

Legend and Explanation

The emojis denote the absolute quality of the code:

• ⭐ excellent
• 🙂 good
• 😞 poor
• ⛔ very poor

The 👍 and 👎 indicate whether the quality has improved or gotten worse with this pull request.

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Please see our documentation here for details on how these metrics are calculated.

We are actively working on this report - lots more documentation and extra metrics to come!

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