Add README (#3)

Author: rutvijmehta-harness

README.md

@@ -1 +1,25 @@
-# drone-buildx-acr
+# drone-buildx-acr
+
+## Build
+
+Build the binaries with the following commands:
+
+```console
+go build ./cmd/drone-buildx-acr
+./drone-buildx-acr
+```
+
+## Usage
+
+### Running from the CLI
+
+```console
+export PLUGIN_TAG=latest
+export PLUGIN_REPO=octocat/hello-world
+export DRONE_COMMIT_SHA=d8dbe4d94f15fe89232e0402c6e8a0ddf21af3ab
+./drone-buildx-acr
+```
+
+## Release procedure
+
+Create your pull request for the release. Get it merged then tag the release. The release will be published and changelog will be generated.