v0.4.0

a6e382d (HEAD -> master, origin/master) Improve the development pipeline using Skaffold.
bd1a194 Add example Kubernetes manifests.
5296b84 Fix incorrect operators in the Grafana dashboard's queries. Fix #6.
e202e1a Cleanup and upgrade dependencies.
0cf8f15 Update the dashboard's screenshot.
66d9591 Update the docs and make it clearer. Fix #4.
34b9473 Fix a potential bug that may cause empty data points in detail panels and upgrade the dashboard format to conform to Grafana 7.0.
22da4a9 Improve the documentation.
39eb972 Fix some gauges ​​of the Grafana dashboard were calculated incorrectly when inbound and user existed simultaneously.
16e522c Improve the dashboard.
96e92d5 Update the dashboard screenshot.
19898ce Improve the dashboard.