Fix Hash's initial_capacity documentation

[wooster0]

#8017 changed the default initial_capacity to 8.

[bew]

Just an idea, since this is a rather arbitrary value afaik, we could have it in a constant INITIAL_CAPACITY, and in the documentation refer to it using a macro {{ INITIAL_CAPACITY }} to avoid these kind of desynchronization between the code and the docs?

[wooster0]

That doesn't sound too bad but I'm pretty sure that would require wrapping the entire constructors with {% begin %} and {% end %} and then that could become pretty ugly when there's also additional indentation in the {% begin %} and {% end %}. I'm not sure it's worth the complexity and I doubt the initial capacity is changing that often.

[straight-shoota]

The default capacity actually isn't really important for users. It's an implementation detail. It's worth mentioning it, but not exposing it as a constant.

[bew]

We could use a private constant to not expose this, but you're right, it's probably not worth the burden

[straight-shoota]

Thank you @r00ster91 ❤️