Fixed typo in ssl.h
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index ba499d2..69fc502 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -1146,7 +1146,7 @@
  *
  * \note           See the documentation of \c mbedtls_ssl_set_timer_t and
  *                 \c mbedtls_ssl_get_timer_t for the conventions this pair of
- *                 callbacks must fallow.
+ *                 callbacks must follow.
  *
  * \note           On some platforms, timing.c provides
  *                 \c mbedtls_timing_set_delay() and