docker: add slim image

docker/README.md

@@ -6,8 +6,10 @@ SFTPGo provides an official Docker image, it is available on both [Docker Hub](h
 
 - [v1.2.0, v1.2, v1, latest](https://github.com/drakkan/sftpgo/blob/v1.2.0/Dockerfile)
 - [v1.2.0-alpine, v1.2-alpine, v1-alpine, alpine](https://github.com/drakkan/sftpgo/blob/v1.2.0/Dockerfile.alpine)
-- [edge](../Dockerfile)
-- [edge-alpine](../Dockerfile.alpine)
+- [edge](../Dockerfile.full)
+- [edge-alpine](../Dockerfile.full.alpine)
+- [edge-slim](../Dockerfile)
+- [edge-alpine-slim](../Dockerfile.alpine)
 
 ## How to use the SFTPGo image
 
@@ -121,6 +123,10 @@ This image is based on the popular [Alpine Linux project](https://alpinelinux.or
 
 This variant is highly recommended when final image size being as small as possible is desired. The main caveat to note is that it does use [musl libc](https://musl.libc.org/) instead of [glibc and friends](https://www.etalabs.net/compare_libcs.html), so certain software might run into issues depending on the depth of their libc requirements. However, most software doesn't have an issue with this, so this variant is usually a very safe choice. See [this Hacker News comment thread](https://news.ycombinator.com/item?id=10782897) for more discussion of the issues that might arise and some pro/con comparisons of using Alpine-based images.
 
+### `sftpgo:<suite>-slim`
+
+These tags provide a slimmer image that does not include the optional `git` and `rsync` dependencies.
+
 ## Helm Chart
 
 An helm chart is [available](https://artifacthub.io/packages/helm/sagikazarmark/sftpgo). You can find the source code [here](https://github.com/sagikazarmark/helm-charts/tree/master/charts/sftpgo).