doc: update clk_flags requirement for i2c docs

Merges https://github.com/espressif/esp-idf/pull/7637

docs/en/api-reference/peripherals/i2c.rst

@@ -87,7 +87,7 @@ Configuration example (master):
         .scl_io_num = I2C_MASTER_SCL_IO,         // select GPIO specific to your project
         .scl_pullup_en = GPIO_PULLUP_ENABLE,
         .master.clk_speed = I2C_MASTER_FREQ_HZ,  // select frequency specific to your project
-        // .clk_flags = 0,          /*!< Optional, you can use I2C_SCLK_SRC_FLAG_* flags to choose i2c source clock here. */
+        .clk_flags = 0,                          // you can use I2C_SCLK_SRC_FLAG_* flags to choose i2c source clock here
     };
 
 .. only:: SOC_I2C_SUPPORT_SLAVE
@@ -105,6 +105,7 @@ Configuration example (master):
             .mode = I2C_MODE_SLAVE,
             .slave.addr_10bit_en = 0,
             .slave.slave_addr = ESP_SLAVE_ADDR,      // address of your project
+            .clk_flags = 0,
         };
 
 At this stage, :cpp:func:`i2c_param_config` also sets a few other I2C configuration parameters to default values that are defined by the I2C specification. For more details on the values and how to modify them, see :ref:`i2c-api-customized-configuration`.