Fix formatting in ChangeLog for version 0.21

Author: RKBoss6

apps/sleeplog/ChangeLog

@@ -16,6 +16,7 @@
 0.18: Add back as a function to prevent translation making it a menu entry
 0.19: Write sleep state into health event's .activity field
 0.20: Increase default sleep thresholds, tweak settings to allow higher ones to be chosen
-0.21: Use HRM data is polling is enabled, and add appropriate thresholds in settings. Change settings to feel more intuitive, rather than copied settings in different pages.
+0.21: Use HRM data if polling is enabled, and add appropriate thresholds in settings. Change settings to feel more intuitive, rather than copied settings in different pages.
 0.22: Fix bug with HRM threshold not updating due to movement thresholds being incorrectly compared against the HRM thresholds.
 0.23: Fix important bug with HRM data being undefined when compared - broken apps should work properly now
+0.24: Change day title to be easier to read, capitalization, and improved documentation/tuning guide in README.