added notes on where to change XTAL freq

Merges https://github.com/espressif/esp-idf/pull/1458

docs/get-started/index.rst

@@ -285,7 +285,7 @@ To exit the monitor use shortcut ``Ctrl+]``.
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         ~zY��Y(1�,1�� e���)(Xn@�y.!Dr�zY(�jpi�|�+z5Ymvp
 
-    or monitor fails shortly after upload, your board is likely using 26MHz crystal, while the ESP-IDF assumes default of 40MHz. Exit the monitor, go back to the :ref:`menuconfig <get-started-configure>`, change :ref:`CONFIG_ESP32_XTAL_FREQ_SEL` to 26MHz, then :ref:`build and flash <get-started-build-flash>` the application again.
+    or monitor fails shortly after upload, your board is likely using 26MHz crystal, while the ESP-IDF assumes default of 40MHz. Exit the monitor, go back to the :ref:`menuconfig <get-started-configure>`, change :ref:`CONFIG_ESP32_XTAL_FREQ_SEL` to 26MHz, then :ref:`build and flash <get-started-build-flash>` the application again. This is found under ``make menuconfig`` under Component config --> ESP32-specific --> Main XTAL frequency.
 
 To execute ``make flash`` and ``make monitor`` in one go, type ``make flash monitor``. Check section :doc:`IDF Monitor <idf-monitor>` for handy shortcuts and more details on using this application.