fixed typo 'isn't is?' -> 'isn't it?' in test_book/src/individual/code.md

Sableoxide · Sableoxide · commit 534666f55141 · 2025-06-08T23:42:42.000+03:00
diff --git a/test_book/src/individual/code.md b/test_book/src/individual/code.md
@@ -17,7 +17,7 @@ This line contains `inline code` mixed with some other stuff. (LTR)
 ---
 
 ````
-escaping ``` in ```, fun, isn't is?
+escaping ``` in ```, fun, isn't it?
 ````
 
 ---
