Typo fix

CHANGELOG.md

@@ -13,7 +13,7 @@ and `nessai` (!1161) and adding the
 - `bilby.gw.likelihood.relative.RelativeBinningGravitationalWaveTransient` (!1105)
 
 ### Changes
-- Reset the timer for `PyMultiNest` when overwriting an exisiting checkpoint directory (!1163)
+- Reset the timer for `PyMultiNest` when overwriting an existing checkpoint directory (!1163)
 - Cache the computed the noise log likelihood for the `GravitationalWaveTransient` (!1179)
 - Set the reference chirp mass for the multi banded likelihood from the prior when not specified (!1169)
 - Bugfix in the name of the saved ASD file in `Interferometer.save_data` (!1176)