Fix #1421, Correctly format code block terminator (#1491)

The code block didn't terminate properly, causing the markdown to not render correctly on GitHub.

docs/cFE Application Developers Guide.md

@@ -2033,7 +2033,7 @@ SAMPLE_AppData_t  SAMPLE_AppData;  /* Instantiate Task Data */
    /* SAMPLE_AppData.BigPktBuf is no longer a valid pointer */
    ...
 }
-```c  
+```
 
 ## 6.9 Best Practices for using Software Bus