Only register `description` for a command when present
Only register `description` for a command when present

Doing so prevents wonky formatting when `description` isn't set.

aaemnnosttv/wp-cli,aaemnnosttv/wp-cli,shawnhooper/wp-cli,GaryJones/wp-cli,rodrigoprimo/wp-cli,shawnhooper/wp-cli,rodrigoprimo/wp-cli,gitlost/wp-cli,GaryJones/wp-cli,miya0001/wp-cli,aaemnnosttv/wp-cli,2ndkauboy/wp-cli,miya0001/wp-cli,nyordanov/wp-cli,gitlost/wp-cli,nyordanov/wp-cli,nyordanov/wp-cli,GaryJones/wp-cli,2ndkauboy/wp-cli,trepmal/wp-cli,trepmal/wp-cli,trepmal/wp-cli,gedex/wp-cli,gedex/wp-cli,miya0001/wp-cli,shawnhooper/wp-cli,gedex/wp-cli,2ndkauboy/wp-cli,gitlost/wp-cli,rodrigoprimo/wp-cli