Add documentation, cleanup

app/src/sensor/NvidiaSensor.cxx

@@ -0,0 +1,21 @@
+#include <include/nvml.h>
+
+#include <sensor/NvidiaSensor.h>
+
+using namespace std;
+
+NvidiaSensor::NvidiaSensor() { nvmlInit_v2(); }
+NvidiaSensor::~NvidiaSensor() { nvmlShutdown(); }
+
+int NvidiaSensor::value() {
+  nvmlDevice_t device;
+
+  nvmlDeviceGetHandleByIndex_v2(0, &device);
+
+  unsigned int temp;
+  nvmlDeviceGetTemperature(device, NVML_TEMPERATURE_GPU, &temp);
+
+  return static_cast<int>(temp);
+}
+
+string NvidiaSensor::name() { return "GPU"; }