Bad hyperlink on documentation

[Ambro17]

NonNull reference under required field from this page https://docs.graphene-python.org/en/latest/types/scalars/ redirects to an inexistent page, namely:
https://docs.graphene-python.org/en/latest/types/scalars/list-and-nonnull/#nonnull
The correct link is
https://docs.graphene-python.org/en/latest/types/list-and-nonnull/#nonnull

[ekampf]

Can you PR it?

[Ambro17]

Inspecting the element with chrome debugger i see that the href points to
./list-and-nonnull.html#nonnull with /types/scalars/ as working directory.

Changing it to ../list-and-nonnull.html#nonnull makes the link works as expected, resolving to https://docs.graphene-python.org/en/latest/types/list-and-nonnull/#nonnull

Strangely, what works for the online version (double dot) doesn't resolve locally. And viceversa, single dot works locally with make docs but fails on the page..
I've opened a pr for you to check this behaviour #980