Update screenshot [ci skip]

Author: dac514

readme.txt

@@ -41,10 +41,10 @@ Then, activate and configure the plugin at the Network level.
 == Changelog ==
 
 = 0.4.0 =
-* Redirect to the page the user signed in from (network homepage or book homepage)
-* Clarify error message when CAS is set to "Refuse Access"
-* Fix unwanted slashes when button text has apostrophe
-* Fix Travis CI build script
+* Redirect to the page the user signed in from (network homepage or book homepage).
+* Clarify error message when CAS is set to "Refuse Access".
+* Fix unwanted slashes when button text has apostrophe.
+* Fix Travis CI build script.
 
 = 0.3.0 =
 * Demo for Open source Slack channel.