Fix typos in C header files

Signed-off-by: Tobias Nießen <tniessen@tnie.de>
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index fff4240..b1d67f7 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -453,7 +453,7 @@
  *       be overridden, but the wrapper functions mbedtls_aes_decrypt and mbedtls_aes_encrypt
  *       must stay untouched.
  *
- * \note If you use the AES_xxx_ALT macros, then is is recommended to also set
+ * \note If you use the AES_xxx_ALT macros, then it is recommended to also set
  *       MBEDTLS_AES_ROM_TABLES in order to help the linker garbage-collect the AES
  *       tables.
  *
diff --git a/include/mbedtls/ssl_ticket.h b/include/mbedtls/ssl_ticket.h
index a10a434..a83f5e6 100644
--- a/include/mbedtls/ssl_ticket.h
+++ b/include/mbedtls/ssl_ticket.h
@@ -124,7 +124,7 @@
  *                  Recommended value: 86400 (one day).
  *
  * \note            It is highly recommended to select a cipher that is at
- *                  least as strong as the the strongest ciphersuite
+ *                  least as strong as the strongest ciphersuite
  *                  supported. Usually that means a 256-bit key.
  *
  * \note            The lifetime of the keys is twice the lifetime of tickets.