Fix Markdown typo in Web IDE docs

As seen in https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/5399

doc/user/project/web_ide/index.md

 # Web IDE
 
 > [Introduced in](https://gitlab.com/gitlab-org/gitlab-ee/issues/4539) [GitLab Ultimate][ee] 10.4.
-> [Brought to GitLab Core][core](https://gitlab.com/gitlab-org/gitlab-ce/issues/44157) in 10.7.
+> [Brought to GitLab Core](https://gitlab.com/gitlab-org/gitlab-ce/issues/44157) in 10.7.
 
 The Web IDE makes it faster and easier to contribute changes to your projects
 by providing an advanced editor with commit staging.