[Finder] Add note about .gitignore rules precedence

Author: julienfalque

components/finder.rst

@@ -148,6 +148,14 @@ can reuse those rules to exclude files and directories from the results with the
     // excludes files/directories matching the .gitignore patterns
     $finder->ignoreVCSIgnored(true);
 
+Rules from higher levels will be overridden by those in lower levels.
+
+.. note::
+
+    Only ``.gitignore`` files from search directories and their descendants are
+    read. Files from parent directories are ignored. To be consistent with Git
+    behavior, you should explicitly search from the Git repository root.
+
 .. versionadded:: 5.4
 
     ``.gitignore`` files recursive support was introduced in Symfony 5.4.