Merge pull request #188 from redis-developer/ajeetraina-patch-2

Update index-usingprometheus.mdx

Author: Simon Prickett

docs/howtos/redistimeseries/using-prometheus/index-usingprometheus.mdx

@@ -15,7 +15,6 @@ A time-series database is a database system designed to store and retrieve such
 
 ### When do you use a time-series database?
 
-- When do you use a time-series database?
 - When your application needs data that accumulates quickly and your other databases aren’t designed to handle that scale.
 - For financial or industrial applications.
 - When your application needs to perform real-time analysis of billions of records.