roles/archweb: Fix some typos

roles/archweb/templates/archweb-mirrorcheck.service.j2

 [Unit]
-Description=archewb mirrorcheck
+Description=archweb mirrorcheck service
 After=network.target
 
 [Service]

roles/archweb/templates/archweb-mirrorresolv.service.j2

 [Unit]
-Description=archewb mirrorresolv service
+Description=archweb mirrorresolv service
 After=network.target
 
 [Service]

roles/archweb/templates/archweb-populate_signoffs.service.j2

 [Unit]
-Description=archewb populate_signoffs service
+Description=archweb populate_signoffs service
 After=network.target
 
 [Service]