add list of supported api's for baremetal

docs/baremetal_api.md

@@ -1 +1,47 @@
 ## Bare metal APIs
+
+Mbed OS bare metal supports the following APIs:
+
+<h3 id="analog-i-o">Analog I/O</h3>
+
+- AnalogIn - Read the voltage applied to an analog input pin.
+- AnalogOut - Set the voltage of an analog output pin.
+
+<h3 id="digital-i-o">Digital I/O</h3>
+
+- DigitalIn - Configure and control a digital input pin.
+- DigitalOut - Configure and control a digital output pin.
+- DigitalInOut - Bidirectional digital pins.
+
+- BusIn - Flexible way to read multiple DigitalIn pins as one value.
+- BusOut - Flexible way to write multiple DigitalOut pins as one value.
+- BusInOut - Flexible way to read and write multiple DigitalInOut pins as one value.
+
+- PortIn - Fast way to read multiple DigitalIn pins as one value.
+- PortOut - Fast way to write multiple DigitalOut pins as one value.
+- PortInOut - Fast way to read and write multiple DigitalInOut pins as one value.
+
+- PwmOut - Pulse-width modulated output.
+
+- InterruptIn - Trigger an event when a digital input pin changes.
+
+<h3 id="timers">Timers</h3>
+
+- Timer - Create, start, stop and read a timer.
+- Timeout - Call a function after a specified delay.
+- Ticker - Repeatedly call a function.
+
+- Wait - Wait for a specified time.
+- Time - Get and set the realtime clock.
+
+<h3 id="digital-interfaces">Digital Interfaces</h3>
+
+- Serial - Serial/UART bus.
+
+- SPI - SPI bus master.
+- SPISlave - SPI bus slave.
+
+- I2C - I²C bus master.
+- I2CSlave - I²C bus slave.
+
+- CAN - Controller-area network bus.