Add Changelog (#100)

.chglog/CHANGELOG.tpl.md

+{{ if .Versions -}}
+<a name="unreleased"></a>
+## [Unreleased]
+{{ if .Unreleased.CommitGroups -}}
+{{ range .Unreleased.CommitGroups -}}
+### {{ .Title }}
+{{ range .Commits -}}
+- {{ if .Scope }}**{{ .Scope }}:** {{ end }}{{ .Subject }}
+{{ end }}
+{{ end -}}
+{{ else }}
+{{ range .Unreleased.Commits -}}
+- {{ if .Scope }}**{{ .Scope }}:** {{ end }}{{ .Subject }}
+{{ end }}
+{{ end -}}
+{{ end -}}
+
+{{ range .Versions }}
+<a name="{{ .Tag.Name }}"></a>
+## {{ if .Tag.Previous }}[{{ .Tag.Name }}]{{ else }}{{ .Tag.Name }}{{ end }} - {{ datetime "2006-01-02" .Tag.Date }}
+{{ if .CommitGroups -}}
+{{ range .CommitGroups -}}
+### {{ .Title }}
+{{ range .Commits -}}
+- {{ if .Scope }}**{{ .Scope }}:** {{ end }}{{ .Subject }}
+{{ end }}
+{{ end -}}
+{{ else }}
+{{ range .Commits -}}
+- {{ if .Scope }}**{{ .Scope }}:** {{ end }}{{ .Subject }}
+{{ end }}
+{{ end -}}
+
+{{- if .NoteGroups -}}
+{{ range .NoteGroups -}}
+### {{ .Title }}
+{{ range .Notes }}
+{{ .Body }}
+{{ end }}
+{{ end -}}
+{{ end -}}
+{{ end -}}
+
+{{- if .Versions }}
+[Unreleased]: {{ .Info.RepositoryURL }}/compare/{{ $latest := index .Versions 0 }}{{ $latest.Tag.Name }}...HEAD
+{{ range .Versions -}}
+{{ if .Tag.Previous -}}
+[{{ .Tag.Name }}]: {{ $.Info.RepositoryURL }}/compare/{{ .Tag.Previous.Name }}...{{ .Tag.Name }}
+{{ end -}}
+{{ end -}}
+{{ end -}}
\ No newline at end of file

.chglog/config.yml

+style: github
+template: CHANGELOG.tpl.md
+info:
+  title: CHANGELOG
+  repository_url: https://github.com/terraform-aws-modules/terraform-aws-rds
+options:
+  header:
+    pattern: "^(.*)$"
+    pattern_maps:
+      - Subject

Makefile

+.PHONY: changelog release
+
+changelog:
+	git-chglog -o CHANGELOG.md --next-tag `semtag final -s minor -o`
+
+release:
+	semtag final -s minor