Fix sloppy wording around stricly less-than vs less or equal

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/include/mbedtls/net_sockets.h b/include/mbedtls/net_sockets.h
index 310b397..702e93f 100644
--- a/include/mbedtls/net_sockets.h
+++ b/include/mbedtls/net_sockets.h
@@ -157,7 +157,7 @@
  *
  * \note           The current implementation of this function uses
  *                 select() and returns an error if the file descriptor
- *                 is beyond \c FD_SETSIZE.
+ *                 is \c FD_SETSIZE or greater.
  *
  * \param ctx      Socket to check
  * \param rw       Bitflag composed of MBEDTLS_NET_POLL_READ and
@@ -242,7 +242,7 @@
  *
  * \note           The current implementation of this function uses
  *                 select() and returns an error if the file descriptor
- *                 is beyond \c FD_SETSIZE.
+ *                 is \c FD_SETSIZE or greater.
  *
  * \param ctx      Socket
  * \param buf      The buffer to write to