openrc, rc-status, rc-service, rc-update: add pages (#3800)

* rc-status: add page

* openrc: add page

* rc-service: add page

* rc-update: add page

* rc-status: add list all runlevels example

* openrc: fix travis errors

* rc-status: fix travis errors again

* Update pages/linux/rc-update.md

Co-Authored-By: Zlatan Vasović <zlatanvasovic@gmail.com>

* Update pages/linux/rc-status.md

Co-Authored-By: Zlatan Vasović <zlatanvasovic@gmail.com>

Co-authored-by: Zlatan Vasović <zlatanvasovic@gmail.com>

pages/linux/rc-status.md

@@ -0,0 +1,32 @@
+# rc-status
+
+> Show status info about runlevels.
+> See also `openrc`.
+
+- Show a summary of services and their status:
+
+`rc-status`
+
+- Include services in all runlevels in the summary:
+
+`rc-status --all`
+
+- List services that have crashed:
+
+`rc-status --crashed`
+
+- List manually started services:
+
+`rc-status --manual`
+
+- List supervised services:
+
+`rc-status --supervised`
+
+- Get the current runlevel:
+
+`rc-status --runlevel`
+
+- List all runlevels:
+
+`rc-status --list`