Update screenshots

README.md

@@ -31,28 +31,28 @@ Screenshots:
 The "My Checks" screen. Shows the status of all your cron jobs
 in a live-updating dashboard.
 
-![Screenshot of My Checks page](/static/img/my_checks@2x.png?raw=true "My Checks Page")
+![Screenshot of My Checks page](/static/img/my_checks.png?raw=true "My Checks Page")
 
 Each check has configurable Period and Grace Time parameters. Period is the expected
 time between pings. Grace Time specifies how long to wait before sending out alerts
 when a job is running late.
 
-![Screenshot of Period/Grace dialog](/static/img/period_grace@2x.png?raw=true "Period/Grace Dialog")
+![Screenshot of Period/Grace dialog](/static/img/period_grace.png?raw=true "Period/Grace Dialog")
 
 Alternatively, you can define the expected schedules using a cron expressions.
 Healthchecks uses the [cronsim](https://github.com/cuu508/cronsim) library to
 parse and evaluate cron expressions.
 
-![Screenshot of Cron dialog](/static/img/cron%402x.png?raw=true "Cron Dialog")
+![Screenshot of Cron dialog](/static/img/cron.png?raw=true "Cron Dialog")
 
 Check details page, with a live-updating event log.
 
-![Screenshot of Check Details page](/static/img/check_details@2x.png?raw=true "Check Details Page")
+![Screenshot of Check Details page](/static/img/check_details.png?raw=true "Check Details Page")
 
 Healthchecks provides status badges with public but hard-to-guess URLs.
 You can use them in your READMEs, dashboards, or status pages.
 
-![Screenshot of Badges page](/static/img/badges@2x.png?raw=true "Status Badges")
+![Screenshot of Badges page](/static/img/badges.png?raw=true "Status Badges")
 
 
 ## Setting Up for Development