[perfmon] Fix typo in variable name

Signed-off-by: Guillaume <guillaume.thouvenin@vates.tech>

Author: gthvn1

python3/bin/perfmon

@@ -940,11 +940,11 @@ class SRMonitor(ObjectMonitor):
             num seconds this alarm disabled after an alarm is sent (default '3600')
        * consolidation_fn:
             how to combine variables from rrd_updates into one value
-            (default is 'get_percent_sr_usage' for 'physical_utilistation',
+            (default is 'get_percent_sr_usage' for 'physical_utilisation',
             & 'sum' for everything else)
        * rrd_regex matches the names of variables
          from (xe sr-data-sources-list uuid=$sruuid) used to compute value
-         (has default for "physical_utilistaion")
+         (has default for "physical_utilisation")
     """
 
     def __init__(self, *args):