It's a hell of a lot better than telling me to install and configure any service dependencies you have (databases, say) outside a container. 'Cuz I'm definitely not going to crap up my system doing that. I'm also not likely to install an entire development environment I don't otherwise need just to run your thing. Just make it a "docker-compose up" for me to install all that junk, or something similarly clean and easy, or it won't happen. Bonus: much higher likelihood that it won't break due to some local environment issue you didn't account for, so lower chance of having your beautiful program fall on its face right out of the gate. Use Vagrant I guess (is that still a thing?) if you're worried about the reviewers not having/wanting Docker or similar, though it's a bigger PITA to configure than Docker and usually takes longer to start up. The point is the concept (keeping your build/run env from crapping up my system in any way that requires me to run more than one or two really easy to discover commands to entirely undo, and ensuring your build/program can run in as many plausible environments as possible without stumbling) not the specific tech.
If you don't have any such dependencies (great!), your build environment's really simple, and you're confident the build's reproducible on my machine without containerizing it then don't do that, hence the "if relevant". If you can leave it running on Heroku or something instead that's fine, but documentation-wise the #1 thing I usually want to see, aside from WTF it's for, is a set of instructions (it can be "run 'make && make install'", that's fine, but tell me) for how to build & run the project that actually work if I follow them. That includes programs that run server-side, the authors of which seem to be the worst about not providing such instructions. Even if I don't try it out, seeing credible-looking well-written directions for those most basic of interactions with your project is comforting and will be among the first things I look for.
TL;DR the point is your README should prominently contain answers to the questions "how do I build this?" and "how do I run this?" and you should make the answers as painless and easy to undo as possible.
[EDIT] and yeah, my fault for not making that TL;DR the entire original statement and avoiding discussion of the not-that-important particulars entirely.