Cockroach: ui: hardware dashboard: add tooltips

[vilterp]

Add descriptive tooltips to each graph in the Hardware Metrics dashboard. Should also update docs to match them. (And maybe link to the docs page on this dashboard…? cc @Amruta-Ranade)

[Amruta-Ranade]

Yes..however, I haven't documented the new graphs yet. Will get to it asap.

[vilterp]

I think we've settled on the final set of graphs at this point. If anything read/write time and IOPS per second would be removed, but probably not.

[Amruta-Ranade]

@vilterp I need help understanding the new graphs.

[piyush-singh]

@Amruta-Ranade proposing some tooltips here based on your docs in cockroachdb/docs#3744

CPU Percent - Percentage of CPU in use by the CockroachDB process. 100% utilization indicates all cores are fully utilized.
Memory Usage - Memory in use by CockroachDB.
Disk Read Bytes - The ten-second moving average of the number of bytes read per second by all processes, including CockroachDB.
Disk Write Bytes - The ten-second moving average of the number of bytes written per second by all processes, including CockroachDB.
Disk Read Ops - The ten-second moving average of the number of disk read ops per second for all processes, including CockroachDB.
Disk Write Ops - The ten-second moving average of the number of disk write ops per second for all processes, including CockroachDB.
Disk IOPS in progress - The number of disk reads and writes in queue for all processes, including CockroachDB.
Available Disk Capacity - Storage capacity available to CockroachDB
Network Bytes Received - The ten-second moving average of the number of network bytes received per second for all processes, including CockroachDB.
Network Bytes Sent - The ten-second moving average of the number of network bytes sent per second for all processes, including CockroachDB.

[piyush-singh]

cc @couchand

[vilterp]

Thanks for writing these @piyush-singh!