Improve wording in documentation of mbedtls_cipher_setup()
diff --git a/include/mbedtls/cipher.h b/include/mbedtls/cipher.h
index 8dc55f9..5051c12 100644
--- a/include/mbedtls/cipher.h
+++ b/include/mbedtls/cipher.h
@@ -394,9 +394,8 @@
 
 
 /**
- * \brief               This function initializes and fills the cipher-context
- *                      structure with the appropriate values. It also clears
- *                      the structure.
+ * \brief               This function initializes a cipher context for
+ *                      use with the given cipher primitive.
  *
  * \param ctx           The context to initialize. May not be NULL.
  * \param cipher_info   The cipher to use.