update README.md [skip ci]

README.md

@@ -1,2 +1,42 @@
 # snowid
+
+![workflow badge](https://github.com/guoyk93/snowid/actions/workflows/go.yml/badge.svg) [![Go Reference](https://pkg.go.dev/badge/github.com/guoyk93/snowid.svg)](https://pkg.go.dev/github.com/guoyk93/snowid)
+
 A concurrent-safe lock-free implementation of snowflake algorithm in Golang
+
+## Get
+
+`go get -u github.com/guoyk93/snowflake`
+
+## Usage
+
+```go
+// assign a unique identifier
+id, _ := strconv.ParseUint(os.Getenv("WORKER_ID"), 10, 64)
+
+// create a instance
+s := snowflake.New(snowflake.Options{
+    Epoch: time.Date(2020, time.January, 1, 0, 0, 0, 0, time.UTC),
+    ID: id,
+})
+
+// get a id
+s.NewID()
+
+// stop and release all related resource
+s.Stop()
+```
+
+## Performance
+
+Less than `1us/op`
+
+## Upstream
+
+https://git.guoyk.net/go-guoyk/snowflake
+
+Due to various reasons, codebase is detached from upstream.
+
+## Credits
+
+Guo Y.K., MIT License