feat: add upgrade doc

Author: Yozhef

UPGRADE-1.0.md

@@ -22,7 +22,8 @@ $ composer update "macpaw/symfony-health-check-bundle" -with-all-dependencies
 Step 2: Update the Symfony Health Check Bundle via Composer
 ----------------------------------
 
-##Automatical:
+## Automatical
+
 Over time - and especially when you upgrade to a new version of a library - an updated version of the recipe may be available. These updates are usually minor - e.g. new comments in a configuration file - but it's a good idea to keep your files in sync with the recipes.
 
 Symfony Flex provides several commands to help upgrade your recipes. Be sure to commit any unrelated changes you're working on before starting:
@@ -39,7 +40,7 @@ $ composer recipes:install symfony/framework-bundle --force -v
 
 The tricky part of this process is that the recipe "update" does not perform any intelligent "upgrading" of your code. Instead, the updates process re-installs the latest version of the recipe which means that your custom code will be overridden completely. After updating a recipe, you need to carefully choose which changes you want, and undo the rest.
 
-##Manual:
+## Manual:
 
 ### Old Config:
 `config/packages/symfony_health_check.yaml`