Apply suggestions from code review

Co-authored-by: Andreas Motl <andreas.motl@crate.io>

docs/performance/inserts/tuning.rst

@@ -130,15 +130,16 @@ value.
 Calculating statistics
 ----------------------
 
-After loading larger amounts of data into new or exiting tables, it is recommended
-to (re-)calculate the statistics by executing the ``ANALYZE`` command. 
+After loading larger amounts of data into new or existing tables, it is recommended
+to re-calculate the statistics by executing the ``ANALYZE`` command. 
 The statistics will be used by the query optimizer to generate better execution plans. 
 
-This calculation of statistics is performed periodically and the maximum amount of bytes 
-per second that can be read from data nodes for the collection of statistics are throttled.
+The calculation of statistics happens periodically. The bandwidth used for collecting statistics
+is limited by applying throttling based on the maximum amount of bytes per second that can
+be read from data nodes.
 
 Please refer to the `ANALYZE`_ documentation for further information how to change the
-calculation interval and how to configure the throttling. 
+calculation interval, and how to configure throttling settings.
 
 Manual optimizing
 -----------------