Add auto-generated code markers

The presence of these markers in the original code was helpful to me in
figuring out that this portion of the code is auto-generated.
Therefore, I think those are useful and should be present.

Signed-off-by: Gaurav Aggarwal <aggarg@amazon.com>
diff --git a/include/mbedtls/error.h b/include/mbedtls/error.h
index 3f0af04..cff22ea 100644
--- a/include/mbedtls/error.h
+++ b/include/mbedtls/error.h
@@ -132,7 +132,7 @@
  *        representation.
  *
  * This function returns a const pointer to an un-modifiable string. The caller
- * must not try to modify the string use it only for logging purposes.
+ * must not try to modify the string and use it only for logging purposes.
  *
  * \param error_code    error code
  *