Add support for post_install_script (#25683)

This is supported in gitops but not referenced in docu.

docs/Configuration/yaml-files.md

@@ -349,6 +349,7 @@ Use `labels_include_any` to target hosts that have any label in the array or `la
 - `pre_install_query.path` is the osquery query Fleet runs before installing the software. Software will be installed only if the [query returns results](https://fleetdm.com/tables) (default: `""`).
 - `install_script.path` specifies the command Fleet will run on hosts to install software. The [default script](https://github.com/fleetdm/fleet/tree/main/pkg/file/scripts) is dependent on the software type (i.e. .pkg).
 - `uninstall_script.path` is the script Fleet will run on hosts to uninstall software. The [default script](https://github.com/fleetdm/fleet/tree/main/pkg/file/scripts) is dependent on the software type (i.e. .pkg).
+- `post_install_script.path` is the script Fleet will run on hosts after the software install. There is no default.
 - `self_service` specifies whether or not end users can install from **Fleet Desktop > Self-service**.
 
 #### Example
@@ -361,6 +362,8 @@ install_script:
   path: ../lib/software/tailscale-install-script.ps1
 uninstall_script:
   path: ../lib/software/tailscale-uninstall-script.ps1
+post_install_script:
+  path: ../lib/software/tailscale-config-script.ps1
 self_service: true
 ```