docs: add release guide to documentation

[mojomex]

PR Type

• Improvement

Related Links

Description

This PR adds a "Cutting Releases" page to the "Contributing" section of the documentation.
Releases are now using the ROS 2 Bloom and Catkin tooling, and I already screwed up using it correctly for version 1.1.0, so documentation is definitely needed 😁

Review Procedure

Build and serve docs with

sudo apt install doxygen
pip3 install -r docs/requirements.txt
mkdocs build --config-file scripts/mkdoxy_gen.yml
python3 scripts/preprocess_zensical_docs.py
zensical serve --config-file .zensical.toml

then go to http://localhost:8000/nebula/contributing/cutting_releases/

Remarks

Pre-Review Checklist for the PR Author

PR Author should check the checkboxes below when creating the PR.

• Assign PR to reviewer

Checklist for the PR Reviewer

Reviewers should check the checkboxes below before approval.

• Commits are properly organized and messages are according to the guideline
• (Optional) Unit tests have been written for new behavior
• PR title describes the changes

Post-Review Checklist for the PR Author

PR Author should check the checkboxes below before merging.

• All open points are addressed and tracked via issues or tickets

CI Checks

• Build and test for PR: Required to pass before the merge.