More concise PSI metrics description

Co-authored-by: James Thompson <[email protected]>

Author: alpineQ

model/system/metrics.yaml

@@ -578,14 +578,10 @@ groups:
       The metric represents the percentage of time that tasks were stalled on a given resource
       over the specified time window.
 
-      The "some" stall type indicates at least some tasks are stalled on the resource.
-      The "full" stall type indicates all non-idle tasks are stalled simultaneously, representing
-      a more severe state where the system is thrashing and CPU cycles are wasted.
-
       PSI is available on Linux systems with kernel 4.20 or later and requires CONFIG_PSI=y.
       CPU "full" stall is reported as zero at the system level for backward compatibility (available since 5.13).
 
-      Values are percentages in the range [0, 100]. The ratios are tracked over 10-second, 60-second,
+      The ratios are tracked over 10-second, 60-second,
       and 300-second windows.
 
       See [Linux kernel PSI documentation](https://docs.kernel.org/accounting/psi.html) and
@@ -620,9 +616,6 @@ groups:
       of latency spikes that wouldn't necessarily make a noticeable impact on time averages.
       It also enables calculating average trends over custom time frames.
 
-      The "some" stall type indicates at least some tasks are stalled on the resource.
-      The "full" stall type indicates all non-idle tasks are stalled simultaneously.
-
       PSI is available on Linux systems with kernel 4.20 or later and requires CONFIG_PSI=y.
       CPU "full" stall is reported as zero at the system level for backward compatibility (available since 5.13).