Fix minor Kramdown warnings

Fix a couple of malformed links that displeased Kramdown.

doc/topics/cron/index.md

@@ -24,7 +24,7 @@ Cron scheduling uses a series of five numbers, separated by spaces:
 # * * * * * <command to execute>
 ```
 
-[Source: [Wikipedia](https://en.wikipedia.org/wiki/Cron)]
+(Source: [Wikipedia](https://en.wikipedia.org/wiki/Cron))
 
 In cron syntax, the asterisk (`*`) means 'every,' so the following cron strings
 are valid:

doc/user/project/import/bitbucket_server.md

@@ -89,7 +89,7 @@ Alternatively, if there is also no email address, the project creator is set as
 
 User assignment by username is under development and not ready for production use. It is
 deployed behind a feature flag that is **disabled by default**.
-[GitLab administrators with access to the GitLab Rails console](<replace with path to>/administration/feature_flags.md)
+[GitLab administrators with access to the GitLab Rails console](../../../administration/feature_flags.md)
 can enable it.
 
 To enable it: