docs(skills): remove stale templates repo pointer from README (#8974)

The `../templates` entry under "Related repositories" claimed
create-objectstack still consumes objectstack-ai/templates as a
scaffold source. Both halves are false: the repository was delisted
from the official marketplace and is no longer maintained (maintainer,
2026-08-14), and #8693 removed the tarball-fetch consumption path from
create-objectstack entirely. Nothing in this repo currently consumes
that repository, so the entry is removed rather than reworded.

Fixes #8694

Co-authored-by: Claude <noreply@anthropic.com>

Author: os-zhuang

skills/README.md

@@ -112,6 +112,3 @@ A few common decision points where the right skill isn't obvious:
 ## Related repositories
 
 - [`../objectui`](https://github.com/objectstack-ai/objectui) — Studio UI (separate repo).
-- [`../templates`](https://github.com/objectstack-ai/templates) — template library
-  consumed by `create-objectstack` (separate repo). Scaffolds reference these
-  skills; keep this index in sync when adding or renaming a skill.