Fix errors in CHANGELOG.md re release v4.21.2

Fixes #120

Author: delphidabbler

CHANGELOG.md

@@ -6,10 +6,10 @@ Releases are listed in reverse version number order.
 
 > Note that _CodeSnip_ v4 was developed in parallel with v3 for a while. As a consequence some v3 releases have later release dates than early v4 releases.
 
-## Release v4.21.2 of 13 July 2023
+## Release v4.21.2 of 14 July 2023
 
 * Removed broken links and fixed unsafe links in the About box [issue #105].
-* Fixed bug in version information files that resulted in an error in the Comments section of the version information of both editions of _CodeSnip_ [issue 106].
+* Fixed bug in version information files that resulted in an error in the Comments section of the version information of both editions of _CodeSnip_ [issue #106].
 * Fixed potential XSS vulnerability in JQuery code used in Easter egg [issue #107].
 * Documentation changes:
   * Rationalised, corrected, updated and clarified licensing information. These changes affected many documentation files. [issue #108].