Adding a new document that is the checklist to make (#975)

* Adding a new document that is the checklist to make

a new `tokenizers` release.
This will help making sure nothing is forgotten.

* Update RELEASE.md

Co-authored-by: SaulLu <55560583+SaulLu@users.noreply.github.com>

* Update RELEASE.md

Co-authored-by: Luc Georges <McPatate@users.noreply.github.com>

* Update RELEASE.md

Co-authored-by: Luc Georges <McPatate@users.noreply.github.com>

* Update RELEASE.md

Co-authored-by: Luc Georges <McPatate@users.noreply.github.com>

* Adding runnning full test suite instructions.

Co-authored-by: SaulLu <55560583+SaulLu@users.noreply.github.com>
Co-authored-by: Luc Georges <McPatate@users.noreply.github.com>

RELEASE.md

@@ -0,0 +1,90 @@
+## How to release
+
+# Before the release
+
+Simple checklist on how to make releases for `tokenizers`.
+
+- Freeze `master` branch.
+- Run all tests (Check CI has properly run)
+- If any significant work, check benchmarks:
+  - `cd tokenizers && cargo bench` (needs to be run on latest release tag to measure difference if it's your first time)
+- Run all `transformers` tests. (`transformers` is a big user of `tokenizers` we need
+  to make sure we don't break it, testing is one way to make sure nothing unforeseen
+  has been done.)
+  - Run all fast tests at the VERY least (not just the tokenization tests). (`RUN_PIPELINE_TESTS=1 CUDA_VISIBLE_DEVICES=-1 pytest -sv tests/`)
+  - When all *fast*  tests work, then we can also (it's recommended) run the whole `transformers`
+  test suite. 
+    - Rebase this [PR](https://github.com/huggingface/transformers/pull/16708).
+        This will create new docker images ready to run the tests suites with `tokenizers` from the main branch.
+    - Wait for actions to finish
+    - Rebase this [PR](https://github.com/huggingface/transformers/pull/16712)
+        This will run the actual full test suite.
+    - Check the results.
+- **If any breaking change has been done**, make sure the version can safely be increased for transformers users (`tokenizers` version need to make sure users don't upgrade before `transformers` has). [link](https://github.com/huggingface/transformers/blob/main/setup.py#L154)
+  For instance `tokenizers>=0.10,<0.11` so we can safely upgrade to `0.11` without impacting
+  current users
+- Then start a new PR containing all desired code changes from the following steps.
+- You will `Create release` after the code modifications are on `master`.
+
+# Rust
+
+- `tokenizers` (rust, python & node) versions don't have to be in sync but it's
+  very common to release for all versions at once for new features.
+- Edit `Cargo.toml` to reflect new version
+- Edit `CHANGELOG.md`:
+    - Add relevant PRs that were added (python PRs do not belong for instance).
+    - Add links at the end of the files.
+- Go to [Releases](https://github.com/huggingface/tokenizers/releases)
+- Create new Release:
+    - Mark it as pre-release
+    - Use new version name with a new tag (create on publish) `vX.X.X`.
+    - Copy paste the new part of the `CHANGELOG.md`
+- ⚠️  Click on `Publish release`. This will start the whole process of building a uploading
+  the new version on `crates.io`, there's no going back after this
+- Go to the [Actions](https://github.com/huggingface/tokenizers/actions) tab and check everything works smoothly.
+- If anything fails, you need to fix the CI/CD to make it work again. Since your package was not uploaded to the repository properly, you can try again.
+
+
+# Python
+
+- Edit `bindings/python/setup.py` to reflect new version.
+- Edit `bindings/python/py_src/tokenizers/__init__.py` to reflect new version.
+- Edit `CHANGELOG.md`:
+    - Add relevant PRs that were added (node PRs do not belong for instance).
+    - Add links at the end of the files.
+- Go to [Releases](https://github.com/huggingface/tokenizers/releases)
+- Create new Release:
+    - Mark it as pre-release
+    - Use new version name with a new tag (create on publish) `python-vX.X.X`.
+    - Copy paste the new part of the `CHANGELOG.md`
+- ⚠️  Click on `Publish release`. This will start the whole process of building a uploading
+  the new version on `pypi`, there's no going back after this
+- Go to the [Actions](https://github.com/huggingface/tokenizers/actions) tab and check everything works smoothly.
+- If anything fails, you need to fix the CI/CD to make it work again. Since your package was not uploaded to the repository properly, you can try again.
+- This CI/CD has 3 distinct builds, `Pypi`(normal), `conda` and `extra`. `Extra` is REALLY slow (~4h), this is normal since it has to rebuild many things, but enables the wheel to be available for old Linuxes
+
+# Node
+
+- Edit `bindings/node/package.json` to reflect new version.
+- Edit `CHANGELOG.md`:
+    - Add relevant PRs that were added (python PRs do not belong for instance).
+    - Add links at the end of the files.
+- Go to [Releases](https://github.com/huggingface/tokenizers/releases)
+- Create new Release:
+    - Mark it as pre-release
+    - Use new version name with a new tag (create on publish) `node-vX.X.X`.
+    - Copy paste the new part of the `CHANGELOG.md`
+- ⚠️  Click on `Publish release`. This will start the whole process of building a uploading
+  the new version on `npm`, there's no going back after this
+- Go to the [Actions](https://github.com/huggingface/tokenizers/actions) tab and check everything works smoothly.
+- If anything fails, you need to fix the CI/CD to make it work again. Since your package was not uploaded to the repository properly, you can try again.
+
+
+# Testing the CI/CD for release
+
+
+If you want to make modifications to the CI/CD of the release GH actions, you need
+to : 
+- **Comment the part that uploads the artifacts** to `crates.io`, `PyPi` or `npm`.
+- Change the trigger mecanism so it can trigger every time you push to your branch.
+- Keep pushing your changes until the artifacts are properly created.