Add leading example sentence in C4066, C4067, and C4077 warning reference

Author: Rageking8

docs/error-messages/compiler-warnings/compiler-warning-level-1-c4067.md

@@ -15,6 +15,8 @@ The compiler found and ignored extra characters following a preprocessor directi
 
 ## Example
 
+The following example generates C4067:
+
 ```cpp
 // C4067a.cpp
 // compile with: cl /EHsc /DX /W1 /Za C4067a.cpp

docs/error-messages/compiler-warnings/compiler-warning-level-1-c4077.md

@@ -17,6 +17,8 @@ The compiler ignores the pragma and leaves the stack checking unchanged.
 
 ## Example
 
+The following example generates C4077:
+
 ```cpp
 // C4077.cpp
 // compile with: /W1 /LD

docs/error-messages/compiler-warnings/compiler-warning-level-3-c4066.md

@@ -15,6 +15,8 @@ The compiler processes only the first character of a wide-character constant.
 
 ## Example
 
+The following example generates C4066:
+
 ```cpp
 // C4066.cpp
 // compile with: /W3