doc/check-health: update notifications

---- ✂️ ----
⚡📉 Health warning: voltage

The voltage on MikroTik jumped more than 10%.

old value: 16.2V
new value: 12.4V
---- ✂️ ----
🔥 Health warning: temperature

The temperature on MikroTik is above threshold: 51°C
---- ✂️ ----
✅ Health recovery: temperature

The temperature on MikroTik dropped below threshold: 47°C
---- ✂️ ----
❌ Health warning: psu1-state

The power supply unit 'psu1-state' on MikroTik failed!
---- ✂️ ----
✅ Health recovery: psu1-state

The power supply unit 'psu1-state' on MikroTik recovered!
---- ✂️ ----

1 files changed, 5 insertions, 5 deletions

diff --git a/doc/check-health.md b/doc/check-health.md
index 9ee16bb..d84693a 100644
--- a/doc/check-health.md
+++ b/doc/check-health.md
@@ -27,17 +27,17 @@ hardware supports:
 
 #### Voltage
 
-![check-health notification voltage](check-health.d/notification-01-voltage.svg)
+![check-health notification voltage](check-health.d/notification-01-voltage.avif)
 
 #### Temperature
 
-![check-health notification](check-health.d/notification-02-temperature-high.svg)  
-![check-health notification](check-health.d/notification-03-temperature-ok.svg)
+![check-health notification](check-health.d/notification-02-temperature-high.avif)  
+![check-health notification](check-health.d/notification-03-temperature-ok.avif)
 
 #### PSU state
 
-![check-health notification](check-health.d/notification-04-psu-fail.svg)  
-![check-health notification](check-health.d/notification-05-psu-ok.svg)
+![check-health notification](check-health.d/notification-04-psu-fail.avif)  
+![check-health notification](check-health.d/notification-05-psu-ok.avif)
 
 Requirements and installation
 -----------------------------