Fix "Run in Colab" and "Download Notebook" links in tutorials

Description

Fixes the links to run tutorials in Colab and to download notebooks.

Motivation and Context

close #2134

[x] I have raised an issue to propose this change (required for new features and bug fixes)

Types of changes

What types of changes does your code introduce? Remove all that do not apply:

[x] Bug fix (non-breaking change which fixes an issue)
[ ] New feature (non-breaking change which adds core functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to change)
[ ] Documentation (update in the documentation)
[ ] Example (update in the folder of examples)

Checklist

Go over all the following points, and put an x in all the boxes that apply. If you are unsure about any of these, don't hesitate to ask. We are here to help!

[x] I have read the CONTRIBUTION guide (required)
[x] My change requires a change to the documentation.
[ ] I have updated the tests accordingly (required for a bug fix or a new feature).
[x] I have updated the documentation accordingly.

:link: Helpful Links

:test_tube: See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/rl/2268

:page_facing_up: Preview Python docs built from this PR

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:heavy_exclamation_mark: 1 Active SEVs

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Checkout action fails due to incompatible GLIBC

:x: 3 New Failures, 11 Pending, 5 Unrelated Failures

As of commit 9b38cf6df67330cc6fdf262f0bef39f3e82fbd72 with merge base ba6897df160bf757e7aa7af921b28810974eb668 ():

NEW FAILURES - The following jobs have failed:

* [Continuous Benchmark (PR) / GPU Pytest benchmark](https://hud.pytorch.org/pr/pytorch/rl/2268#27034470879) ([gh](https://github.com/pytorch/rl/actions/runs/9785956403/job/27034470879)) `Workflow failed! Resource not accessible by integration` * [Habitat Tests on Linux / tests (3.9, 12.1) / linux-job](https://hud.pytorch.org/pr/pytorch/rl/2268#27034472748) ([gh](https://github.com/pytorch/rl/actions/runs/9785956418/job/27034472748)) `RuntimeError: Command docker exec -t 934c2a462827d233e76ffbe82f3d684be6b0c18249b718d5edea2696f46f7c58 /exec failed with exit code 139` * [RLHF Tests on Linux / unittests (3.9, 12.1) / linux-job](https://hud.pytorch.org/pr/pytorch/rl/2268#27034473821) ([gh](https://github.com/pytorch/rl/actions/runs/9785956426/job/27034473821)) `RuntimeError: vmap: It looks like you're attempting to use a Tensor in some data-dependent control flow. We don't support that yet, please shout over at https://github.com/pytorch/functorch/issues/257 .`

FLAKY - The following jobs failed but were likely due to flakiness present on trunk:

* [Continuous Benchmark (PR) / CPU Pytest benchmark](https://hud.pytorch.org/pr/pytorch/rl/2268#27034470115) ([gh](https://github.com/pytorch/rl/actions/runs/9785956403/job/27034470115)) (detected as infra flaky with no log or failing log classifier) * [Wheels / build-wheel-linux (3.10, cp310-cp310, --index-url https://download.pytorch.org/whl/cpu, "['cpu', ...](https://hud.pytorch.org/pr/pytorch/rl/2268#27034471560) ([gh](https://github.com/pytorch/rl/actions/runs/9785956396/job/27034471560)) ([similar failure](https://hud.pytorch.org/pytorch/rl/commit/9b38cf6df67330cc6fdf262f0bef39f3e82fbd72#27034470115)) * [Wheels / build-wheel-linux (3.11, cp311-cp311, --index-url https://download.pytorch.org/whl/cpu, "['cpu', ...](https://hud.pytorch.org/pr/pytorch/rl/2268#27034473833) ([gh](https://github.com/pytorch/rl/actions/runs/9785956396/job/27034473833)) ([similar failure](https://hud.pytorch.org/pytorch/rl/commit/9b38cf6df67330cc6fdf262f0bef39f3e82fbd72#27034470115)) * [Wheels / build-wheel-linux (3.8, cp38-cp38, --index-url https://download.pytorch.org/whl/cpu, "['cpu', '11...](https://hud.pytorch.org/pr/pytorch/rl/2268#27034470322) ([gh](https://github.com/pytorch/rl/actions/runs/9785956396/job/27034470322)) ([similar failure](https://hud.pytorch.org/pytorch/rl/commit/9b38cf6df67330cc6fdf262f0bef39f3e82fbd72#27034470115)) * [Wheels / build-wheel-linux (3.9, cp39-cp39, --index-url https://download.pytorch.org/whl/cpu, "['cpu', '11...](https://hud.pytorch.org/pr/pytorch/rl/2268#27034470791) ([gh](https://github.com/pytorch/rl/actions/runs/9785956396/job/27034470791)) ([similar failure](https://hud.pytorch.org/pytorch/rl/commit/9b38cf6df67330cc6fdf262f0bef39f3e82fbd72#27034470115))

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pytorch / rl