Update README.md with usefull information

I have added more informations on how to keep the repo updated:
- how to update the framework
- how to update the tarballs
The changes have been requested in this issue #1

Author: Franky5831

README.md

@@ -12,4 +12,57 @@ For more information, see the [CodeIgniter 4 Installation Guide](https://codeign
 
 ```
 ddev config --name=testpkgcodeigniter4 --project-type=codeigniter --docroot=public
-```
+```
+
+## Update the repo
+
+### Update the framework
+
+Most updates require you to manually update configuration files like `app/Config/App.php` or `app/Config/Filters.php`, the easiest way to update this test project is to start over.
+1. Delete all the files from the framework: **make sure you're in the project directory**
+```bash
+# will delete everything except for README.md, .gitignore and the .git (the only two file that is not from the framework)
+find . -maxdepth 1 ! -name 'README.md' ! -name '.gitignore' ! -name '.git' ! -name '.' -exec rm -rf {} +
+```
+2. Create a new project:
+```bash
+composer create-project codeigniter4/appstarter project-root
+```
+3. Copy the contents of the directory in which you created the app to the root dir:
+```bash
+rsync -av --exclude='README.md' --exclude='.gitignore' --exclude='.git' project-root/ ./
+```
+4. Delete the directory in which you created the app:
+```bash
+rm -rf project-root/
+```
+
+### update tarballs
+
+#### Database tarball (`db.sql.tar.gz`)
+The database tarball contains the output of running migrations on a fresh CodeIgniter 4 install (creates an empty migrations table).
+
+To create/update:
+```bash
+# Run migrations to create the database structure
+php spark migrate
+
+# Export the database (adjust credentials as needed)
+mysqldump -u root -p db > db.sql
+
+# Create the tarball
+tar -czf db.sql.tar.gz db.sql
+
+# Clean up
+rm db.sql
+```
+
+#### Files tarball (`files.tar.gz`)
+The files tarball contains the readme.md and welcome page assets used in ddev/ddev tests.
+
+To create/update:
+```bash
+tar -czf files.tar.gz files
+```
+
+**Note:** These tarballs are used by the automated tests in the main ddev/ddev repository.