Point "Coding with AI agents" links at the rendered docs site (#13952)

CONTRIBUTING.md is a symlink to docs/source/en/conceptual/contribution.md.
GitHub renders a symlink blob as a path stub, not the target's content, so
the `#coding-with-ai-agents` anchor in the PR template and README landed on
an empty-looking page. Point those two anchored links at the rendered docs
site instead (the same URL the PR-issue-reminder bot already uses).

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: yiyixuxu

.github/PULL_REQUEST_TEMPLATE.md

@@ -17,7 +17,7 @@ Fixes # (issue)
 
 ## Before submitting
 - [ ] Did you use an AI agent (Claude Code, Codex, Cursor, etc.) to help with this PR? If so:
-  - [ ] Did you point it at the project conventions in [`.ai/`](https://github.com/huggingface/diffusers/tree/main/.ai) (e.g. via `make claude` / `make codex`)? See [Coding with AI agents](https://github.com/huggingface/diffusers/blob/main/CONTRIBUTING.md#coding-with-ai-agents).
+  - [ ] Did you point it at the project conventions in [`.ai/`](https://github.com/huggingface/diffusers/tree/main/.ai) (e.g. via `make claude` / `make codex`)? See [Coding with AI agents](https://huggingface.co/docs/diffusers/main/en/conceptual/contribution#coding-with-ai-agents).
   - [ ] Did you self-review the diff against [`.ai/review-rules.md`](https://github.com/huggingface/diffusers/blob/main/.ai/review-rules.md)?
 - [ ] Did you read the [contributor guideline](https://github.com/huggingface/diffusers/blob/main/CONTRIBUTING.md)?
 - [ ] Did you read our [philosophy doc](https://github.com/huggingface/diffusers/blob/main/PHILOSOPHY.md)? (important for complex PRs)

README.md

@@ -112,7 +112,7 @@ Check out the [Quickstart](https://huggingface.co/docs/diffusers/quicktour) to l
 
 We ❤️  contributions from the open-source community!
 If you want to contribute to this library, please check out our [Contribution guide](https://github.com/huggingface/diffusers/blob/main/CONTRIBUTING.md).
-If you are using an AI agent, please point it at the project conventions in [`.ai/`](https://github.com/huggingface/diffusers/tree/main/.ai) first (run `make claude` or `make codex`) — see [Coding with AI agents](https://github.com/huggingface/diffusers/blob/main/CONTRIBUTING.md#coding-with-ai-agents).
+If you are using an AI agent, please point it at the project conventions in [`.ai/`](https://github.com/huggingface/diffusers/tree/main/.ai) first (run `make claude` or `make codex`) — see [Coding with AI agents](https://huggingface.co/docs/diffusers/main/en/conceptual/contribution#coding-with-ai-agents).
 You can look out for [issues](https://github.com/huggingface/diffusers/issues) you'd like to tackle to contribute to the library.
 - See [Good first issues](https://github.com/huggingface/diffusers/issues?q=is%3Aopen+is%3Aissue+label%3A%22good+first+issue%22) for general opportunities to contribute
 - See [New model/pipeline](https://github.com/huggingface/diffusers/issues?q=is%3Aopen+is%3Aissue+label%3A%22New+pipeline%2Fmodel%22) to contribute exciting new diffusion models / diffusion pipelines