Adding release checklist (#734)

* Adding release checklist

* Update release_checklist.md

Co-authored-by: Devang Gaur <devang.gaur@accurics.com>

* small tweak to release checklist

Co-authored-by: Devang Gaur <devang.gaur@accurics.com>

release_checklist.md

@@ -0,0 +1,37 @@
+# Release Checklist
+This file provides a guideline on steps that need to be taken to properly release a new version of Terrascan:
+
+### Run unit & integration tests
+The following command will kick off both unit tests and end-to-end tests. These tests should finish clean before a release is made:
+
+```
+make cicd
+```
+
+### Bump version in source code
+Once tests look clean, edit `pkg/version/version.go` and update the version number around line 20.
+
+### Update Changelog
+Running the following command will generate new entries in `CHANGELOG.md` since _since-tag_. They will be placed in the changelog file under a heading related to _future-release_. In the example below, changelogs will be generated for any changes since the `v1.4.0` tag, and placed under a section titled *v1.5.0*.
+
+Before running this command, you'll need to have a GitHub [personal access token](https://docs.github.com/en/github/authenticating-to-github/creating-a-personal-access-token) set in the `GITHUB_TOKEN` OS environment variable.
+
+```
+docker run -it --rm -v "$(pwd)":/usr/local/src/your-app ferrarimarco/github-changelog-generator -u accurics -p terrascan -t $GITHUB_TOKEN -b CHANGELOG.md --since-tag v1.4.0 --future-release v1.5.0
+```
+
+Next, Review `CHANGELOG.md` to ensure there are notes for the new release
+
+Once complete, commit changes and submit a pull request. This should be the last PR before cutting the release.
+
+### Tag the new release with git
+Once the changelog PR has been merged, pull the updated code, tag it with the new version number, and push the tag back to the repo:
+
+(again, subsitute v1.5.0 for the appropriate version being released)
+```
+git pull
+git tag v1.5.0
+git push
+```
+
+This will kick off the GitHub workflow to run goreleaser to perform the release.