Section headings are using system default font rather than Lato

[roraback]

Page headings currently use system default font. Should be using Lato. See screenshot below and focus in on the 'g': body text and nav are using Lato; heading is system default:

Confirmed in inspector:

[ptgott]

Note for when we resolve this: the gravitational/docs site configures Lato fonts here:

https://github.com/gravitational/docs/blob/0b723cb6cf750e02d9b4869ede1dd5c890888a0b/pages/_app.tsx