Update retrieve.md

Author: ViktarStarastsenka

src/ds/ts/retrieve.md

@@ -1,5 +1,3 @@
-## Basic data retrieval commands
-
 ### The `TS.GET` command
 
 `TS.GET` is used to get the sample with the highest timestamp from a given time series. It reports both the timestamp and the value.
@@ -124,4 +122,4 @@ The `GROUPBY` syntax is: `GROUPBY label REDUCE reducer`. The available reducer f
 
 ```redis TS.MRANGE with GROUPBY/REDUCE
 TS.MRANGE - + WITHLABELS COUNT 5 FILTER region=(east) GROUPBY region REDUCE sum
-```
+```