add release instructions

Signed-off-by: Josh Dolitsky <jdolitsky@gmail.com>

Author: jdolitsky

.goreleaser.yml

@@ -0,0 +1,16 @@
+builds:
+- main: ./cmd/oras
+  binary: ./bin/oras
+  env:
+  - CGO_ENABLED=0
+  goos:
+  - darwin
+  - linux
+  - windows
+  goarch:
+  - amd64
+
+archive:
+  format: tar.gz
+  files:
+  - LICENSE

BUILDING.md

@@ -0,0 +1,13 @@
+# Developer Guide
+
+## Cutting a new release
+
+Use [goreleaser](https://goreleaser.com/):
+
+Example of releasing `v0.1.0`:
+```
+git tag -a v0.1.0 -m "Release v0.1.0"
+git push origin v0.1.0
+goreleaser
+```
+