fix typo

Author: omahs

readme.md

@@ -102,7 +102,7 @@ Security information for administering a BookStack instance can be found on the
 
 If you'd like to be notified of new potential security concerns you can [sign-up to the BookStack security mailing list](https://updates.bookstackapp.com/signup/bookstack-security-updates).
 
-If you would like to report a security concern, details of doing so can [can be found here](https://github.com/BookStackApp/BookStack/blob/development/.github/SECURITY.md).
+If you would like to report a security concern, details of doing so [can be found here](https://github.com/BookStackApp/BookStack/blob/development/.github/SECURITY.md).
 
 ## ♿ Accessibility