change directory structure to match index

Signed-off-by: Michel-FK <michel.stempin@funkey-project.com>

docs/developer_guide/hardware_reference/magnetic_switch.md

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+The **FunKey S** features no ON/OFF switch. Instead, a small magnet
+placed near the LCD screen in the lid is detected using a magnetic
+sensor that is placed in front of it when the lid is closed.
+
+The magnetic sensor controls the PMIC N_OE (Negative logic Output
+Enable) input, which turns off all voltage rails except the +3.3V
+Always On when the signal is at the high level.
+
+We thus need a sensor that will close when a magnetic field is
+detected, and in order to reduce power consumption when the **FunKey
+S** is turned off and preserve its battery when stored on a shelf, it
+should be a fully passive device. This rules out magnetic Hall effect
+sensors, wich require some power for their operation.
+
+The only practical solution is to use a "Reed switch", which is a
+relatively thin flexible piece of metal inside the switch envelope
+that is sensitive to a magnetic field, which opens or closes a contact
+accordingly.
+
+Most of the Reed switch available are made of a tiny glass tube, which
+is rather fragile and may break if the device falls on the floor,
+something quite usual for a keychain...
+
+We found only a unique plastic-molded model which almost meets our
+low-profile requirements of 1.5 mm (1.6 mm height!): the [Standex
+Meder MK24][1].
+
+Here is the corresponding schematics, already covered in the PMIC
+discussion:
+
+![Magnetic Sensor Schematics](/assets/images/Magnetic_Sensor_Schematics.png){.lightbox}
+
+The global PMIC chip enable signal N_OE is activated by default
+through a 47kΩ resistor **R17** to GND, but the magnetic Reed switch
+**S14** can disable it by forcing its level to +VOUT, with a filter
+capacitor **C83**.
+
+[1]: https://github.com/FunKey-Project/FunKey-S-Hardware/blob/master/Datasheets/MK24_V02.pdf
+
+--8<--
+includes/glossary.md
+--8<--