Update data_formats.rst (#1034)

* Update data_formats.rst

Very minor grammatical corrections.

* Update docs/text/data_formats.rst

---------

Co-authored-by: Nils Braun <[email protected]>

docs/text/data_formats.rst

@@ -19,13 +19,13 @@ make up those DataFrames. Each will be described with an example from the robot
 
 :`column_id`: This column indicates which entities the time series belong to. Features will be extracted individually
     for each entity (id). The resulting feature matrix will contain one row per id.
-    Each robot is a different entity, so each of it has a different id.
+    Each robot is a different entity, so each of the set of features has a different id.
 
-:`column_sort`: This column contains values which allow to sort the time series (e.g. time stamps).
-    In general, it is not required to have equidistant time steps or the same time scale for the different ids and/or kinds.
-    Some features might make however only sense for equidistant time stamps.
+:`column_sort`: This column contains values which allows sorting of the time series (e.g. sorting by time stamps).
+    In general, having equidistant time steps, or the same time scale for the different ids and/or kinds, is not a requirement.
+    Some features, however, might only sense for equidistant time stamps.
     If you omit this column, the DataFrame is assumed to be already sorted in ascending order.
-    Each of the robot sensor measurements have a time stamp which is used as the `column_sort`.
+    Each of the robot sensor measurements has a time stamp which is used as the `column_sort`.
 
 Need only to be specified on some data formats (see below):