scollectd: Add optional description to registered counters
scollectd: Add optional description to registered counters

dreamsxin/seastar,kjniemi/seastar,dreamsxin/seastar,avikivity/seastar,cloudius-systems/seastar,syuu1228/seastar,dreamsxin/seastar,syuu1228/seastar,syuu1228/seastar,avikivity/seastar,scylladb/seastar,scylladb/seastar,cloudius-systems/seastar,kjniemi/seastar,scylladb/seastar,kjniemi/seastar,avikivity/seastar,cloudius-systems/seastar