Iterate on changelog and readme

Author: jrfnl

README.md

@@ -41,6 +41,16 @@ vendor/bin/phpcs -i
 If all went well, you will now see that the `PHPCompatibility` and `PHPCompatibilityPasswordCompat` standards are installed for PHP_CodeSniffer.
 
 
+## Upgrade instructions
+
+To upgrade this package, run the following command:
+```bash
+composer update --dev phpcompatibility/phpcompatibility-passwordcompat --with-dependencies
+```
+
+If you have a _root_ requirement in your project for one of the packages used by this project, you may need to update with `--with-all-dependencies` instead.
+
+
 ## How to use
 
 Now you can use the following command to inspect the code in your project for PHP cross-version compatibility: