add internal sensors documentation to appendix and create new internal sensors overview (#1161)

Author: AtsushiSakai

docs/modules/12_appendix/appendix_main.rst

@@ -10,5 +10,6 @@ Appendix
    steering_motion_model
    Kalmanfilter_basics
    Kalmanfilter_basics_2
+   internal_sensors
    external_sensors
 

docs/modules/12_appendix/external_sensors_main.rst

@@ -1,6 +1,10 @@
 External Sensors for Robots
 ============================
 
+This project, `PythonRobotics`, focuses on algorithms, so hardware is not included.
+However, having basic knowledge of hardware in robotics is also important for understanding algorithms.
+Therefore, we will provide an overview.
+
 Introduction
 ------------
 

docs/modules/12_appendix/internal_sensors_main.rst

@@ -0,0 +1,32 @@
+Internal Sensors for Robots
+============================
+
+This project, `PythonRobotics`, focuses on algorithms, so hardware is not included.
+However, having basic knowledge of hardware in robotics is also important for understanding algorithms.
+Therefore, we will provide an overview.
+
+Introduction
+------------
+
+Global Navigation Satellite System (GNSS)
+-------------------------------------------
+
+Gyroscope
+----------
+
+Accelerometer
+--------------
+
+Magnetometer
+--------------
+
+Inertial Measurement Unit (IMU)
+--------------------------------
+
+Pressure Sensor
+-----------------
+
+Temperature Sensor
+--------------------
+
+