docs: add reference for "docker config" commands

This is mostly a copy of the equivalent `docker secret` commands,
which uses the same mechanisms behind the hood (hence, are 90% the
same).

We can make further refinements to these docs, but this gives us
a starting point.

Adding these documents, because there were some links pointing to
these pages in the docs, but there was no markdown file to link to
on GitHub.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

docs/reference/commandline/config_rm.md

@@ -0,0 +1,53 @@
+---
+title: "config rm"
+description: "The config rm command description and usage"
+keywords: ["config, rm"]
+---
+
+# config rm
+
+```Markdown
+Usage:  docker config rm CONFIG [CONFIG...]
+
+Remove one or more configs
+
+Aliases:
+  rm, remove
+
+Options:
+      --help   Print usage
+```
+
+## Description
+
+Removes the specified configs from the swarm.
+
+For detailed information about using configs, refer to [store configuration data using Docker Configs](https://docs.docker.com/engine/swarm/configs/).
+
+> **Note**
+>
+> This is a cluster management command, and must be executed on a swarm
+> manager node. To learn about managers and workers, refer to the
+> [Swarm mode section](https://docs.docker.com/engine/swarm/) in the
+> documentation.
+
+## Examples
+
+This example removes a config:
+
+```bash
+$ docker config rm my_config
+sapth4csdo5b6wz2p5uimh5xg
+```
+
+> **Warning**
+>
+> Unlike `docker rm`, this command does not ask for confirmation before removing
+> a config.
+
+
+## Related commands
+
+* [config create](config_create.md)
+* [config inspect](config_inspect.md)
+* [config ls](config_ls.md)