[basic.life] Fix indentation in example (#6727)

Author: Andreas-Krug

source/basic.tex

@@ -3682,12 +3682,12 @@
 \begin{codeblock}
 class T { };
 struct B {
-   ~B();
+  ~B();
 };
 
 void h() {
-   B b;
-   new (&b) T;
+  B b;
+  new (&b) T;
 }                               // undefined behavior at block exit
 \end{codeblock}
 \end{example}