docs: Document the DDEV install and fix the shipped DDEV config

Problem/Motivation

The README only documented a host-Composer install, and the shipped .ddev/config.yaml was broken.

Steps to reproduce

Scaffold a project from the shipped .ddev/config.yaml and run ddev start: it fails with "Unable to locate package php8.4-yaml"; nodejs_version: "18" also contradicts package.json, which needs Node 20+.

Proposed resolution

README now shows the DDEV flow with drupal/webship_project and ddev drush site:install webship. Fixed .ddev/config.yaml: removed the broken webimage_extra_packages: ["php${DDEV_PHP_VERSION}-yaml"], corrected nodejs_version to 20+, and changed type: drupal11 to drupal. Verified: a scratch project from the shipped config now starts with PHP 8.4 and Node 22.

Remaining tasks

• ✅ File an issue about this project
• ❌ Addition/Change/Update/Fix to this project
• ❌ Testing to ensure no regression
• ➕ Automated unit/functional testing coverage
• ➕ Developer Documentation support on feature change/addition
• ➕ User Guide Documentation support on feature change/addition
• ➕ UX/UI designer responsibilities
• ➕ Accessibility and Readability
• ❌ Reviewed by a human
• ❌ Code review by maintainers
• ❌ Full testing and approval
• ❌ Credit contributors
• ❌ Review with the product owner
• ❌ Update Release Notes
• ❌ Release

User interface changes

• N/A

API changes

• N/A

Data model changes

• N/A

Release notes snippet

• N/A