Add a note banner to each of the six existing Django, Express, FastAPI, Flask, Go and Spring Boot tutorials, linking readers to the corresponding Ubuntu 26.04 guide in the paas-charm documentation. Links explicitly use `/latest/`. The full Ubuntu 26.04 tutorials, fixtures and test wiring are in [canonical/paas-charm#390](https://github.com/canonical/paas-charm/pull/390). This Charmcraft PR now contains only the six banners: 36 added lines, with no other changes to existing tutorial content. It adds no tutorial pages, application code, shared setup, Spread configuration, redirects, index entries or release notes. The linked guides require the separate paas-charm documentation change to be published. ### Validation - The isolated documentation build, focused Sphinx syntax/spelling/terminology checks, six rendered banner-link assertions and commit hooks passed. - `make test-fast`: 2843 passed, 79 deselected, 3 xfailed. - `make format` stops when installing missing tombi requires interactive sudo authentication. - `make lint` reports the same 23 existing Python type diagnostics. - Release notes are not applicable to this documentation-link-only change. --- - [ ] I've followed the [contribution guidelines](https://github.com/canonical/charmcraft/blob/main/CONTRIBUTING.md). - [ ] I've signed the [CLA](http://www.ubuntu.com/legal/contributors/). - [ ] I've successfully run `make lint && make test`. - [x] I've added or updated any relevant documentation. - [ ] In documents I changed, I [added a meta description](https://canonical-starflow.readthedocs-hosted.com/how-to/add-a-page-meta-description/) if one was missing. - [ ] I've updated the relevant release notes.