docs: correct the docs rules and label the Prompt Guide previews

Three things the quality layer asserted but the pages did not support.

changelog-process said "do not recreate docs/weekly-updates.mdx; that empty
public page was retired" while the page exists with a real curated feed. It
describes the page as it is: unlisted, reachable by URL and RSS, with versioned
notes still in the Changelog.

The Related-topics rule read as universal, but three different endings are in
use and each is right for its shape — Related topics on task pages, a single
Next line through the Prompt Guide's numbered sequence, and nothing on
reference and concept pages. The rule now says that, and every section matches
it; color-grading gained the Next line it was missing and no longer points at a
page this stack retired.

The vocabulary previews were 18 DocsVideo players in three unlabelled grids, so
a reader saw several near-identical clips with no way to tell smooth from
snappy. They are now native muted loops with visible captions, which is what
AGENTS.md asks for small preview loops in the first place.

Author: ukimsanov

docs/AGENTS.md

@@ -54,9 +54,18 @@ narrated film a reader watches intentionally. A plain `<video>` is only for a
 small, muted, autoplaying preview loop inside a visual explanation or Catalog
 item. Do not mix native browser controls with the custom player.
 
-**Related topics must be visible content.** Mintlify does not render a
-`related:` frontmatter list. Add a final `## Related topics` section with only
-the two or three destinations that genuinely help the reader continue.
+**End a page by pointing somewhere, and make the pointer visible content.**
+Mintlify does not render a `related:` frontmatter list, so a frontmatter key
+buys nothing. How the pointer looks depends on the page:
+
+- Task, guide, Studio, and Catalog pages end with a `## Related topics` section
+  naming the two or three destinations that genuinely help the reader continue.
+- Pages in a numbered sequence — the Prompt Guide — end with a single
+  `*Next: [page] — why*` line instead. A course has one useful destination, and
+  three competing links break the through-line.
+- Reference and concept pages (`/packages`, `/sdk`, `/reference`, `/concepts`)
+  may end without either. A reader arrives there from one specific question and
+  leaves the same way; inventing three related links is filler.
 
 ### Custom React components
 

docs/contributing/changelog-process.mdx

@@ -99,7 +99,7 @@ This creates internal editorial drafts:
 - `updates/social/2026-06-07.discord.md`
 - `updates/social/2026-06-07.x.md`
 
-Review and rewrite the generated files before publishing anything. Social drafts are never posted automatically. Do not recreate or commit `docs/weekly-updates.mdx`; that empty public page was retired.
+Review and rewrite the generated files before publishing anything. Social drafts are never posted automatically. Curated highlights from these packets go to [Weekly updates](/weekly-updates), which is unlisted in the sidebar and reachable by URL and RSS; exact versioned release notes stay in the [Changelog](/changelog).
 
 ## Writing style
 

docs/prompting/color-grading.mdx

@@ -207,5 +207,7 @@ Two caveats worth knowing before you promise a client a ramp:
 ## Next steps
 
 - [Color Grading guide](/guides/color-grading) — the full contract, every key and bound
-- [Media Overlays](/guides/media-overlays) — HUD, flash, light leak, freeze-frame dressing
+- [Catalog: overlays and effects](/catalog) — HUD, flash, light leak, freeze-frame dressing
 - [VFX and liquid glass](/prompting/vfx-and-liquid-glass) — the canvas-pipeline end of the catalog
+
+*Next: [VFX and liquid glass](/prompting/vfx-and-liquid-glass) — the same grading vocabulary pushed into the canvas pipeline.*