Fix #3149 docs template link + downloads URL reversing bugs

[alvynabranches]

Summary

Single PR with per-issue commits from a full audit (Docker test suite + static review).

Commit 1 — Closes #3149: Incorrect link to new documentation issue

CPython's issue template is documentation.yml, not documentation.md.
The old link in this repo opened a blank template. Updated in:

• .github/ISSUE_TEMPLATE/BUG.yml
• .github/ISSUE_TEMPLATE/DOCS.yml
• .github/ISSUE_TEMPLATE/REQUEST.yml

Verified: https://github.com/python/cpython/tree/main/.github/ISSUE_TEMPLATE contains documentation.yml (no .md).

Commit 2 — Downloads URL reversing bugs (found via audit)

• OS.get_absolute_url used kwarg os_slug, but route download_os_list expects slug (apps/downloads/urls.py:19). Every call raised NoReverseMatch. Fixed in apps/downloads/models.py:58, verified: now returns /downloads/windows/.
• DownloadLatestPython2.get_redirect_url fallback used bare reverse("download") (no such name) — 500 when no Python 2 flagged latest. Fixed to download:download.
• DownloadLatestPyManager.get_redirect_url fallback used bare reverse("downloads") — same 500. Fixed to download:download.
• Standardized DownloadLatestPython3, DownloadLatestPrerelease, and ReleaseFeed.link fallbacks on download:download (both download: and downloads: resolve today, but download: matches the instance namespace used everywhere else).

Added regression tests:

• test_os_get_absolute_url
• test_latest_python2_redirects_to_downloads_when_no_latest
• test_latest_pymanager_redirects_to_downloads_when_no_latest

Issues reviewed with no code change

• Bug: Resolutions in PSF minutes not listed on Resolutions page #2677 (Resolutions missing): no code path — /psf/records/board/resolutions/ is a hand-maintained CMS page (no model/view/URL; minutes app stores a single MarkupField body). Needs CMS edit by staff, not a code PR. Anchor support from anchors for resolutions #3175 already merged.
• Bug: Downloading mail archives from Mailman3 often times out #2847 (Mailman archive timeouts): mail.python.org HyperKitty export infra outside this repo; only nginx redirects to it live here. Needs infra-side timeout/sizing work.
• Bug: Was "linear-code" meant to close many issues without a reason? #3185 (linear-code closing issues): Linear/GitHub bot process, no integration code in this repo.
• Migrate away from EthicalAds #3176 (EthicalAds migration): already covered by open PR Migrate to plausible #3177 (chore/issue-3176-remove-ethicalads). Did not duplicate; that PR still needs a rebase onto main's EA CSP fixes (fix CSP #3183/More CSP fixes for EA #3184).

Verification (per README contributing guide)

• makemigrations --check --dry-run: No changes detected
• ruff check: All checks passed; ruff format --check: 655 files formatted
• Full suite via Docker (coverage run manage.py test): 1072 tests, OK (211s)
• Coverage: 86% (threshold 75%)
• Targeted new tests: 5 tests OK; prior downloads-only run: 122 tests OK

[JacobCoffee]

this does too much, should be scoped PRs please :)

[alvynabranches]

Follow-up audit note (no code changes in this comment):

I swept every literal reverse()/reverse_lazy() call site in non-test code (57 distinct call shapes across apps) and executed each one under Django, plus reviewed the duplicate URL-name report and spot-checked {% url %} tags:

• All call sites resolve. The only script flags were 3 agreements routes (order_detail, detail, custom_detail) that need UUID pks — verified each resolves with a real UUID (e.g. /agreements/orders/<uuid>/).
• The only app-level duplicate URL name is the known download_latest_python3 alias (latest/ vs latest/python3/, under both download and getit namespaces). Both patterns serve the same view and redirect identically, so this is benign; left untouched to avoid churn. (Framework-level duplicates from DRF/tastypie/allauth/sitetree are expected.)
• Template {% url %} tags spot-checked consistent (kwargs match route params); the full suite (1072 tests OK) renders them.

So beyond the two commits in this PR, the audit found no further verified crash-level bugs. Remaining open items (#2677 content, #2847 infra, #3185 process, #3176 covered by #3177) are documented in the PR description as needing non-code handling.