docs(Sticky): add warning about erratic behavior inside Sidebar.Pushable

[brambow]

Sticky elements have erratic behavior inside Sidebar.Pushable.

See: #2897 and #2462
Also see: Semantic-Org/Semantic-UI#1745

This PR adds a warning message in the Sticky docs about this erratic behavior and suggests placing Sticky elements outside any Sidebar.Pushable elements.

[welcome]

💖 Thanks for opening this pull request! 💖

Here is a list of things that will help get it across the finish line:

• Run yarn lint locally to catch formatting errors. This will fix some errors automatically, commit and push any changes.
• Run yarn test locally to catch errors. This ensures all components still behave as they should.
• Run yarn start to run the doc site locally and try a few pages, ensuring everything is in good working order.
• Include tests when adding/changing behavior.

We get a lot of pull requests on this repo, so please be patient and we will get back to you as soon as we can.

[stale]

There has been no activity in this thread for 180 days. While we care about every issue and we’d love to see this fixed, the core team’s time is limited so we have to focus our attention on the issues that are most pressing. Therefore, we will likely not be able to get to this one.

However, PRs for this issue will of course be accepted and welcome!

If there is no more activity in the next 180 days, this issue will be closed automatically for housekeeping. To prevent this, simply leave a reply here. Thanks!

[welcome]

Congrats on merging your first pull request! 🎉🎉🎉

[levithomason]

Released in semantic-ui-react@0.86.0.