Improve grammar ever so slightly

NEWS

@@ -8,7 +8,7 @@ Additions:
 * `events` dataset updated: now contains event counts for each day from 2014-10-17 to 2017-12-31
 * `weather` dataset updated: now contains daily weather report for each day from 2014-10-17 to 2017-12-31, and the format is a bit nicer
 * `get_daily_weather` produces the nicer-format weather table for any given date range (no longer limited to retrieving 398 records in one go...)
-* Add code tests for all main functionality (and add `covr` reporting to Travis)
+* Added code tests for all main functionality (and add `covr` reporting to Travis)
 
 
 
@@ -111,4 +111,4 @@ Additions:
 * Initial release. Datasets of parking records from 2014-16, basic parking record manipulation functions:
   - `get_all_crude` for retrieving dataset of records from Bath: Hacked datastore
   - `refine` for processing the raw records
-  - `refuel` and `refuel_crude` for updating existing data frames with recent records
+  - `refuel` and `refuel_crude` for updating existing data frames with recent records