chore(*): small docstring syntax fixes

[Vierkantor]

This PR goes through and corrects all the warnings raised by linter.style.docStringVerso that are unrelated to LaTeX or link syntax. In addition to putting backticks around some expressions, there are a few typos (such as mismatched brackets, or syntax in the wrong order), a few unusual usages of punctuation (such as putting {} around names in references), and a few usages made consistent (*-ring, C⋆-algebra).

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[github-actions]

PR summary 4fceb4697e

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

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Declarations diff

No declarations were harmed in the making of this PR! 🐙

You can run this locally as follows

## summary with just the declaration names:
./scripts/pr_summary/declarations_diff.sh <optional_commit>

## more verbose report:
./scripts/pr_summary/declarations_diff.sh long <optional_commit>

The doc-module for scripts/pr_summary/declarations_diff.sh contains some details about this script.

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No changes to technical debt.

You can run this locally as

./scripts/reporting/technical-debt-metrics.sh pr_summary

• The relative value is the weighted sum of the differences with weight given by the inverse of the current value of the statistic.
• The absolute value is the relative value divided by the total sum of the inverses of the current values (i.e. the weighted average of the differences).

[jcommelin]

Just as with the AB axioms... What is the correct way to write an asterisk in markdown / verso? Does escaping work?

Suggested change

	the semiring into the centre of the centroid becomes a `*`-homomorphism.
	the semiring into the centre of the centroid becomes a \*-homomorphism.

Idem dito for many other places.

[Vierkantor]

According to grep, we have about twice as many `*`-objects (39) in docstrings compared to *-objects (22). But indeed we could switch over to \*-objects, since both Markdown (CommonMark) and Verso allow backslash-escaping *.

Some more datapoints: looks like Wikipedia writes them as *-objects and the nLab writes them as $*$-objects.

I suppose \*-objects render the most naturally, so let's go for that.

[jcommelin]

Thanks 🎉

bors d+

[mathlib-bors]

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