Fix typo in MbedStats.md

Fix typo.

Author: Amanda Butler

docs/reference/api/platform/MbedStats.md

@@ -21,7 +21,7 @@ You can use the `mbed_stats_sys_get` function to get the CPU ID and compiler inf
 
 You can use the `mbed_stats_cpu_get` function to get the uptime, idle time and sleep time information. Timing information available is cumulative since the system is on. You must build Mbed OS with the `MBED_CPU_STATS_ENABLED` macro to enable fetching of CPU information. Please note CPU statistics depend on the availability of the low power timer in the hardware.
 
-### Mbed statistics functions reference
+### Mbed statistics function reference
 
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