Description
I'm not sure if this is the correct place to raise this issue, but I'm not sure of a better one...
The main documentation website (https://d3js.org/) appears to be configurated correctly, but most of the examples there link to the Observable website (https://observablehq.com/), which is configured such that only TLS 1.3, but not TLS 1.2 traffic can connect.
This means that the Observable website is inaccessible from 1-2% of all browsers on the internet. But also, it's inaccessible through some widely-used corporate firewalls (e.g. ZScaler), that don't support TLS 1.3 yet.
Given that this website isn't just for d3js documentation but is also the front door for the commercial Observable framework, not allowing access to corporations (and potential customers) that use TLS 1.2 firewalls would seem to be problematic.
I would think that configuring https://observablehq.com/ to support both TLS 1.3 AND 1.2 traffic would improve accessibility to the site. This is why 99.9% of websites (per https://www.ssllabs.com/ssl-pulse/) still support TLS 1.2 traffic.