What is the correct casing for help center? If we look at the help center we find the heading in sentence casing with only the first word capitalized (Help center) but if we look further down we see it written with both words capitalized Help Center (Title Case) in Welcome to the Stack Overflow Help Center!
(...) If a feature or product is unique to Stack Overflow, capitalize it (Stack Overflow for Teams, Stack Overflow Jobs).
This happens in other places of the site, for example this breadcrumb has Review Queues with both words capitalized next to Help center with only the first word capitalized. Here we could assume the review queues are a unique feature and the help center doesn't qualify as such. But then why is Title Case used in Welcome to the Stack Overflow Help Center!?
It's worth mentioning that reading through the help-center wiki small case is used. It's safe to say I'm not the only user who isn't sure about this, experienced users in help-center questions use all kinds of casing, so it's not clear if Title Case is the recommended way of stylizing help center or not.