Fix a fairly common typo in comments
diff --git a/include/mbedtls/hmac_drbg.h b/include/mbedtls/hmac_drbg.h
index 4ffc646..e010558 100644
--- a/include/mbedtls/hmac_drbg.h
+++ b/include/mbedtls/hmac_drbg.h
@@ -98,7 +98,7 @@
 
 /**
  * \brief               HMAC_DRBG context initialization
- *                      Makes the context ready for mbetls_hmac_drbg_seed(),
+ *                      Makes the context ready for mbedtls_hmac_drbg_seed(),
  *                      mbedtls_hmac_drbg_seed_buf() or
  *                      mbedtls_hmac_drbg_free().
  *