Updated the document

AsswinCR · web-flow · commit 6183a005e07d · 2021-10-05T18:44:03.000+05:30
diff --git a/lessons/string-builder.md b/lessons/string-builder.md
@@ -5,7 +5,7 @@ order: "6B"
 section: "Strings In Depth"
 description: "learn strings in depth"
 ---
-## Introduction
+
 
 String Builder is a separate class just like Strings, which allows us to modify the values(mutability).
 ### Need of String Builder:
