Add language to code block

Author: Colin Robertson

docs/c-language/c-bit-fields.md

@@ -48,7 +48,7 @@ Bit fields defined as **`int`** are treated as **`signed`**. A Microsoft extensi
 
 Bit fields are allocated within an integer from least-significant to most-significant bit. In the following code
 
-```
+```C
 struct mybitfields
 {
     unsigned short a : 4;