[Backport v1.21] admin: actions: move misplaced nixos section

(cherry picked from commit 2cc8fba302)

docs/admin/actions.md

@@ -102,17 +102,6 @@ environment. They need to be installed and configured independently.
 - **Docker:**
   See [the Docker installation](https://docs.docker.com/engine/install/) documentation for more information.
 
-  IPv6 support is not enabled by default in docker. The following snippet enables this.
-
-  ```nix
-  virtualisation.docker = {
-    daemon.settings = {
-      fixed-cidr-v6 = "fd00::/80";
-      ipv6 = true;
-    };
-  };
-  ```
-
 - **Podman:**
   While Podman is generally compatible with Docker,
   it does not create a socket for managing containers by default
@@ -390,6 +379,17 @@ The [`forgejo-actions-runner`](https://github.com/NixOS/nixpkgs/blob/ac6977498b1
 
 Please note that the `services.forgejo-actions-runner.instances.<name>.labels` key may be set to `[]` (an empty list) to use the packaged Forgejo instance list. One of `virtualisation.docker.enable` or `virtualisation.podman.enable` will need to be set. The default Forgejo image list is populated with docker images.
 
+IPv6 support is not enabled by default for docker. The following snippet enables this.
+
+```nix
+virtualisation.docker = {
+  daemon.settings = {
+    fixed-cidr-v6 = "fd00::/80";
+    ipv6 = true;
+  };
+};
+```
+
 ## Other runners
 
 It is possible to use [other runners](https://codeberg.org/forgejo-contrib/delightful-forgejo#user-content-forgejo-actions-runners) instead of `Forgejo runner`. As long as they can connect to a `Forgejo` instance using the [same protocol](https://codeberg.org/forgejo/forgejo/src/branch/forgejo/routers/api/actions), they will be given tasks to run.