Update DOCtor-RST and enable new rules

- Require DOCtor-RST 1.75.1
- Enable NoNonBreakingSpace rule
- Enable NoEmptyDirective rule
- Enable FilepathAndNamespaceShouldMatch rule with namespace mapping (src/ -> App\ or Acme\, tests/ -> App\Tests\, apps/api/tests/ -> Api\Tests\) and ignore config/ and example.com/ paths

Author: OskarStark

.doctor-rst.yaml

@@ -25,6 +25,7 @@ rules:
         namespace_mapping:
             'src/': ['App\', 'Acme\']
             'tests/': 'App\Tests\'
+            'apps/api/tests/': 'Api\Tests\'
         ignored_paths:
             - '/^config\//'
             - '/^example\.com\//'