Update README

README.md

@@ -2,3 +2,35 @@
 Send a count of Pull-Request as custom metrics to Datadog
 
 [![](https://mermaid.ink/img/eyJjb2RlIjoiZ3JhcGggTFJcbiAgICBBW0dpdEh1Yl1cbiAgICBCW2RhdGFkb2ctZ2l0aHViLXByXVxuICAgIENbRGF0YWRvZ11cbiAgICBCIC0tPnxnZXQgUHVsbCBSZXF1ZXN0c3wgQVxuICAgIEIgLS0-fHNuZWQgYSBjb3VudCBvZiBQdWxsIFJlcXVlc3RzIGFzIGN1c3RvbSBtZXRyaWNzfCBDIiwibWVybWFpZCI6e30sInVwZGF0ZUVkaXRvciI6ZmFsc2V9)](https://mermaid-js.github.io/mermaid-live-editor/#/edit/eyJjb2RlIjoiZ3JhcGggTFJcbiAgICBBW0dpdEh1Yl1cbiAgICBCW2RhdGFkb2ctZ2l0aHViLXByXVxuICAgIENbRGF0YWRvZ11cbiAgICBCIC0tPnxnZXQgUHVsbCBSZXF1ZXN0c3wgQVxuICAgIEIgLS0-fHNuZWQgYSBjb3VudCBvZiBQdWxsIFJlcXVlc3RzIGFzIGN1c3RvbSBtZXRyaWNzfCBDIiwibWVybWFpZCI6e30sInVwZGF0ZUVkaXRvciI6ZmFsc2V9)
+
+## Preparation
+
+Copy .envrc and lod it.
+
+```
+$ cp .envrc.sample .envrc
+$ # edit .envrc
+$ # source .envrc
+```
+
+The target repositories are specified by GITHUB_REPOSITORIES environment varibales, that should be written in org/reponame, separated by commas.
+
+>export GITHUB_REPOSITORIES="chaspy/datadog-github-pr,chaspy/favsearch"
+
+## How to run
+
+### Local
+
+```
+$ go run main.go
+```
+
+### Binary
+
+Get the binary file from [Releases](https://github.com/chaspy/datadog-github-pr/releases) and run it.
+
+### Docker
+
+```
+$ docker run -e DATADOG_API_KEY="${DATADOG_API_KEY}" -e DATADOG_APP_KEY="${DATADOG_APP_KEY}" -e GITHUB_TOKEN="${GITHUB_TOKEN}" -e GITHUB_REPOSITORIES="${GITHUB_REPOSITORIES}" chaspy/datadog-github-pr:v0.1.0
+```