Add leading example sentence for warning references in range [C4231, C4270]

Author: Rageking8

docs/error-messages/compiler-warnings/compiler-warning-level-1-c4251.md

@@ -32,6 +32,8 @@ Think carefully about adding `__declspec(dllexport)` or `__declspec(dllimport)`
 
 ## Example
 
+The following example generates C4251:
+
 ```cpp
 // C4251.cpp
 // Compile with /std:c++20 /EHsc /W2 /c C4251.cpp

docs/error-messages/compiler-warnings/compiler-warning-level-1-c4269.md

@@ -15,6 +15,8 @@ A **`const`** automatic instance of a non-trivial class is initialized with a co
 
 ## Example
 
+The following example generates C4269:
+
 ```cpp
 // C4269.cpp
 // compile with: /c /LD /W1

docs/error-messages/compiler-warnings/compiler-warning-level-2-c4250.md

@@ -19,6 +19,8 @@ Because a virtual base class is shared among multiple derived classes, a name in
 
 ## Examples
 
+The following example generates C4250:
+
 ```cpp
 // C4250.cpp
 // compile with: /c /W2

docs/error-messages/compiler-warnings/compiler-warning-level-3-c4240.md

@@ -15,6 +15,8 @@ Under ANSI compatibility ([/Za](../../build/reference/za-ze-disable-language-ext
 
 ## Example
 
+The following example generates C4240:
+
 ```cpp
 // C4240.cpp
 // compile with: /W3

docs/error-messages/compiler-warnings/compiler-warning-level-4-c4238.md

@@ -15,6 +15,8 @@ For compatibility with previous versions of Visual C++, Microsoft extensions (**
 
 ## Example
 
+The following example generates C4238:
+
 ```cpp
 // C4238.cpp
 // compile with: /W4 /c

docs/error-messages/compiler-warnings/compiler-warning-level-4-c4268.md

@@ -15,6 +15,8 @@ A **`const`** global or static instance of a non-trivial class is initialized wi
 
 ## Example
 
+The following example generates C4268:
+
 ```cpp
 // C4268.cpp
 // compile with: /c /LD /W4