A table of contents (ToC) shows the structure of a page's various sections.
WeWrite won't have a separate UI for the ToC, rather the way to achieve a similar view will be to collapse all sections so that all that remains is the section header. This can be accomplished two ways
double-tapping a section header (a single tap only collapses that section you tapped, double tap collapses all)
long press section header to open menu, one menu option will be "Collapse all sections"
Purposeful limitations
Only one level of hierarchy. No H1, H2, H3, etc. there's only one. I guess you could call it H1.
Want more levels? Create a new pages for things.