Add missing comma

docs/architecture-decisions/0002-extend-timdex-ui-for-gis-data.md

@@ -88,7 +88,7 @@ We will not use index detection, as it does not address any additional use cases
 
 Using the theme gem for header customizations may be useful for other applications. We can minimize repetition by
 managing these changes in environment variables read by the theme gem, but we should be wary of overabstraction. We will
-try this with adding the app name to the header to start and carefully consider whether it may be useful for other UI
+try this with adding the app name to the header to start, and carefully consider whether it may be useful for other UI
 elements.
 
 The feature flag will serve as an initial solution to isolating GDT UI features. Because we have used `flipflop` before,