remove id collision caveat from documentation

doc/development/gotchas.md

@@ -141,51 +141,3 @@ in an initializer._
 ### Further reading
 
 - Stack Overflow: [Why you should not write inline JavaScript](http://programmers.stackexchange.com/questions/86589/why-should-i-avoid-inline-scripting)
-
-## ID-based CSS selectors need to be a bit more specific
-
-Normally, because HTML `id` attributes need to be unique to the page, it's
-perfectly fine to write some JavaScript like the following:
-
-```javascript
-$('#js-my-selector').hide();
-```
-
-However, there's a feature of GitLab's Markdown processing that [automatically
-adds anchors to header elements][ToC Processing], with the `id` attribute being
-automatically generated based on the content of the header.
-
-Unfortunately, this feature makes it possible for user-generated content to
-create a header element with the same `id` attribute we're using in our
-selector, potentially breaking the JavaScript behavior. A user could break the
-above example with the following Markdown:
-
-```markdown
-## JS My Selector
-```
-
-Which gets converted to the following HTML:
-
-```html
-<h2>
-  <a id="js-my-selector" class="anchor" href="#js-my-selector" aria-hidden="true"></a>
-  JS My Selector
-</h2>
-```
-
-[ToC Processing]: https://gitlab.com/gitlab-org/gitlab-ce/blob/8-4-stable/lib/banzai/filter/table_of_contents_filter.rb#L31-37
-
-### Solution
-
-The current recommended fix for this is to make our selectors slightly more
-specific:
-
-```javascript
-$('div#js-my-selector').hide();
-```
-
-### Further reading
-
-- Issue: [Merge request ToC anchor conflicts with tabs](https://gitlab.com/gitlab-org/gitlab-ce/issues/3908)
-- Merge Request: [Make tab target selectors less naive](https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/2023)
-- Merge Request: [Make cross-project reference's clipboard target less naive](https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/2024)