[pre] blocks now preserve spaces

- Added test case
- Added English documentation

tests/src/Content/Text/BBCodeTest.php

@@ -241,6 +241,10 @@ class BBCodeTest extends MockedTest
 				'expectedHtml' => '[test] Space',
 				'text' => '[test] Space',
 			],
+			'task-8800-pre-spaces' => [
+				'expectedHtml' => '    Spaces',
+				'text' => '[pre]    Spaces[/pre]',
+			],
 		];
 	}