Add unit_of_measurement to NEXTCLOUD strings

Hi,
I added the Nextcloud services giving me data from the Nextcloud server.
All data is given in a bar. I found out that using unit_of_measurement it can change into a graph.

On Github I found [core]/[homeassistant]/[components]/[nextcloud]/# strings.json (homeassistant/components/nextcloud/strings.json)

I don’t know anything about compiling, but how can I add a unit_of_measurement to cpuload, so I have a graph?

Thank you in advance!