Document default `host` for `app.listen()`?

[karlhorky]

Hi, first of all, thanks so much for Express and the ecosystem, very foundational project! 🙌

Just wanted to ask whether the Express team would be open to maintaining a sentence in the docs about what the default values are for host when using app.listen() with only a port. Currently, in the Express 4 and 5 docs, only the behavior of an omitted port argument is documented - the behavior when omitting the host is not mentioned:

1. Express 4 docs for app.listen()
2. Express 5 docs for app.listen()

Maybe something similar to the Express 2.0 docs (maybe also with a disambiguation of INADDR_ANY):

When host is omitted all connections will be accepted via INADDR_ANY.

https://expressjs.com/2x/guide.html#:~:text=When%20host%20is%20omitted%20all%20connections%20will%20be%20accepted%20via%20INADDR_ANY.

I guess this issue contains one of the closest descriptions of the behavior here:

• https://github.com/expressjs/expressjs.com/issues/1318