Update reference.md to fix argument name (#1005)

Signed-off-by: LGov <[email protected]>

docs/install/reference.md

@@ -134,7 +134,7 @@ application processing, specify a number of `1`.
 
 **--once**
 
-A shortcut for specifying `--check-interval 0 --health-port 0`. If given,
+A shortcut for specifying `--interval 0 --health-port 0`. If given,
 Argo CD Image Updater will exit after the first update cycle.
 
 **--registries-conf-path *path* **
@@ -144,4 +144,4 @@ Load the registry configuration from file at *path*. Defaults to the path
 default configuration should be used instead, specify the empty string, i.e.
 `--registries-conf-path=""`.
 
-[label selector syntax]: https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#label-selectors
+[label selector syntax]: https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#label-selectors