Documenting a solution for missing classes

See rectorphp/rector#6688

build/target-repository/docs/static_reflection_and_autoload.md

@@ -74,4 +74,19 @@ If the false positive still happen, you can skip the rule applied as last resort
             __DIR__ . '/src/HasChildClass.php',
         ],
     ]);
-```
+```
+
+### Dealing with "Class ... was not found while trying to analyse it..."
+Sometimes you may encounter this error ([see here for an example](https://github.com/rectorphp/rector/issues/6688)) even if the class is there and it seems to work properly with other tools (e.g. PHPStan).
+
+In this case you may want to try one of the following solutions:
+```php
+    $parameters->set(Option::AUTOLOAD_PATHS, [
+        // the path to the exact class file
+        __DIR__ . '/vendor/acme/my-custom-dependency/src/Your/Own/Namespace/TheAffectedClass.php',
+        // or you can specify a wider scope
+        __DIR__ . '/vendor/acme/my-custom-dependency/src',
+        // WARNING: beware of performances, try to narrow down the path
+        //          as much as you can or you will slow down each run
+    ]);
+```