Release 3.34.3 documentation

[TheThingsBot]

Summary

Release 3.34.3 documentation.

Automatic Changes

• Added documentation for 3.34.3.

Manual Changes

• Update the 'featured' section in 'doc/content/whats-new/3.34.3.md' with only selected items that should be featured.
• If the are build errors due to missing message definitions, manually add the new and definitions where necessary.

Checklist for Reviewers

• A new section has been created in 'whats-new' with the corresponding CHANGELOG from TheThingsIndustries/lorawan-stack. The title is the release version and the date is the release date.
• The latest UPGRADING.md from the lorawan-stack-aws has been copied to /the-things-stack/host/aws/ecs/changelog
• The documentation version is up to date with the latest PATCH (3.${minor}.${patch}). No "v" is prefixed.
• The TTI and TTN API documentation has been generated and updated in doc/data/api. This includes the following files:

doc/data/api/tti.lorawan.v3/messages.yml
doc/data/api/tti.lorawan.v3/services.yml
doc/data/api/tti.lorawan.v3/enums.yml
doc/data/api/ttn.lorawan.v3/messages.yml
doc/data/api/ttn.lorawan.v3/services.yml
doc/data/api/ttn.lorawan.v3/enums.yml

• The TTI CLI documentation has been generated and updated in doc/data. This includes the following files:

doc/data/commands/ttn-lw-cli.json
doc/content/ttn-lw-cli/*.md

• All generated documentation matches the version that is being released.

[happyRip]

This is ready for review

[johanstokking]

See https://github.com/TheThingsIndustries/lorawan-stack/pull/4734#pullrequestreview-3343717310, looks like the changelog is not up-to-date.