add drinking water

Overall, it is very easy to use, but there are several problems and suggestions:

1. The values ​​recorded by different users but at the same time will be overwritten.
2. Sometimes I only need to record blood sugar, but blood pressure and pulse are required fields, so I have to enter 1, the line chart is not perfect, and the average value would be inaccurate.
3. I hope to increase the amount of drinking water recorded. The control of high blood pressure also needs to drink more water, which can make this app more perfect.