[stdexcept.syn] Align class declarations

Author: eisenwave

source/diagnostics.tex

@@ -64,14 +64,14 @@
 \begin{codeblock}
 namespace std {
   class logic_error;
-    class domain_error;
-    class invalid_argument;
-    class length_error;
-    class out_of_range;
+  class domain_error;
+  class invalid_argument;
+  class length_error;
+  class out_of_range;
   class runtime_error;
-    class range_error;
-    class overflow_error;
-    class underflow_error;
+  class range_error;
+  class overflow_error;
+  class underflow_error;
 }
 \end{codeblock}