docs: remove removed examples guidelines reference from PR template (#83043)

## For Maintainers

### What?

Removed the references to the now-deleted examples guidelines from the
PR template. Specifically, removed the line about

```
The "examples guidelines" are followed from our contributing doc https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md
``` 
since that file and folder were deleted in PR
[#77050](#77050).

### Why?

The `/examples` folder and its `adding-examples.md` file were removed,
so the reference in the PR template to those guidelines is outdated and
misleading. Keeping those references causes confusion for contributors
by pointing to non-existent documentation.

### How?

- Edited the PR template file.
- Removed the outdated examples guidelines reference line.
- Left other template content unchanged to preserve existing guidance.

This ensures the PR template stays accurate, up-to-date, and helpful for
contributors.

---------

Co-authored-by: Joseph <[email protected]>

Author: wo-o29

.github/pull_request_template.md

@@ -9,11 +9,6 @@ Choose the right checklist for the change(s) that you're making:
 - Run `pnpm prettier-fix` to fix formatting issues before opening the PR.
 - Read the Docs Contribution Guide to ensure your contribution follows the docs guidelines: https://nextjs.org/docs/community/contribution-guide
 
-### Adding or Updating Examples
-
-- The "examples guidelines" are followed from our contributing doc https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md
-- Make sure the linting passes by running `pnpm build && pnpm lint`. See https://github.com/vercel/next.js/blob/canary/contributing/repository/linting.md
-
 ### Fixing a bug
 
 - Related issues linked using `fixes #number`