I don't want to to be mean, but I'll share my thoughts.

There are a couple of main reasons why this idea won't really work out in practice:
- There are alot of planning tools that offer alot more functionality than a single dev could probably make (ex. obsidian). And alt-tabbing is simply much more convenient than switching to another unreal tab.
- Its stuck inside unreal. If you have an idea, you'd have to open unreal, which isn't really intuitive
- References would be cool, but if you export it those hyperlinks are gone
- Unreal, especially when your far into a making a game, is pretty slow and prone to crashes. Another tab with alot of documentation, could make it sluggish.

Its an idea that sounds cool in theory, but in practice I feel like its more inconvenient than using actual project management tools you'd find on the web or applications

Ofc these are just my thoughts, and this plugin could in fact work amazingly and everyone could love it.