Reword ssl_conf_max_frag_len documentation to clarify its necessity
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index 135be05..86ada47 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -2755,13 +2755,18 @@
#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
/**
* \brief Set the maximum fragment length to emit and/or negotiate
- * (Default: the smaller of MBEDTLS_SSL_IN_CONTENT_LEN and
+ * (Typical: the smaller of MBEDTLS_SSL_IN_CONTENT_LEN and
* MBEDTLS_SSL_OUT_CONTENT_LEN, usually 2^14 bytes)
* (Server: set maximum fragment length to emit,
- * usually negotiated by the client during handshake
+ * usually negotiated by the client during handshake)
* (Client: set maximum fragment length to emit *and*
* negotiate with the server during handshake)
*
+ * \note By default the \c mfl_code field ofthe \c mbedtls_ssl_config
+ * structure is equal `0 == MBEDTLS_SSL_MAX_FRAG_LEN_NONE`.
+ * This means the max fragment length extension *will not* be
+ * used unless set to other value via this function.
+ *
* \note With TLS, this currently only affects ApplicationData (sent
* with \c mbedtls_ssl_read()), not handshake messages.
* With DTLS, this affects both ApplicationData and handshake.