characateristic
1. In addition to mentioning in the documentation, use the standard appearance
values already present and return appropriate error in case an incorrect
value is passed
2. Add ESP_BLE_APPEARANCE* macros corresponding to BTM_BLE_APPEARANCE*
and use them from the API instead
3. Add the missing appearance parameter values from
https://www.bluetooth.com/specifications/gatt/viewer?attributeXmlFile=org.bluetooth.characteristic.gap.appearance.xml
4. Fix some minor typos
Signed-off-by: Hrishikesh Dhayagude <hrishi@espressif.com>