[Merged by Bors] - doc(RingTheory): fix local ring doc comment

[vlad902]

The predicate for local rings was updated to the current definition on non-commutative semirings back in mathlib3, but the outdated comment stating that local rings are commutative rings with a unique maximal ideal has not been updated since.

---

[github-actions]

PR summary 8af42bb664

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

---

Declarations diff

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

You can run this locally as follows

## from your `mathlib4` directory:
git clone https://github.com/leanprover-community/mathlib-ci.git ../mathlib-ci

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

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

The doc-module for scripts/pr_summary/declarations_diff.sh in the mathlib-ci repository contains some details about this script.

---

No changes to strong technical debt.

No changes to weak technical debt.

[faenuccio]

Thanks!

bors merge

[mathlib-bors]

Pull request successfully merged into master.

Build succeeded:

• ci (staging) / Post-Build Step
• ci (staging) / Build
• ci (staging) / Lint style
• ci (staging) / Post-CI job