JetBrains: "Learn more" link in install notification points to the wrong URL

Created by: vdavid

Right after installation, this notification comes up:

When I click "Learn More", it shows me this page: https://plugins.jetbrains.com/plugin/9682-sourcegraph The original intention was to link this blog post: https://about.sourcegraph.com/blog/jetbrains-plugin

Context: at the release date, the blog post was not ready, so we just linked the plugin page. Now we've had the blog post for almost two weeks, but we forgot to update the link.

/cc @muratsu @jjinnii @ryankscott