[Merged by Bors] - doc: add docstrings for reversed range telescoping lemmas

[Qinghev]

This PR adds docstrings for two existing Finset telescoping lemmas and their additive versions generated by to_additive:

• Finset.prod_range_div' / Finset.sum_range_sub'
• Finset.eq_prod_range_div / Finset.eq_sum_range_sub

It is documentation-only: no declarations or imports are changed.

CI has passed.

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[github-actions]

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[github-actions]

PR summary 9cdd822a92

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

---

Declarations diff (regex)

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.

Declarations diff (Lean -- pending)

Computed after the build finishes.

---

No changes to strong technical debt.

No changes to weak technical debt.

Current commit 9cdd822a92
Reference commit 7403500b02

This script lives in the mathlib-ci repository. To run it locally, from your mathlib4 directory:

git clone https://github.com/leanprover-community/mathlib-ci.git ../mathlib-ci
../mathlib-ci/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).

[joneugster]

Thanks!

maintainer merge

[github-actions]

🚀 Pull request has been placed on the maintainer queue by joneugster.

[j-loreaux]

bors merge

[mathlib-bors]

Already running a review

[j-loreaux]

oops, misclick.

bors merge

[github-actions]

✅ PR Title Formatted Correctly

The title of this PR has been updated to match our commit style conventions.
Thank you!

[mathlib-bors]

Pull request successfully merged into master.

Build succeeded:

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