Overwrite canonical without html with sphinx extension

[angelinekwan]

What changed, and why it matters

To resolve issue #1691 , canonical url updated to
/index.html -> /
and the rest of the pages without .html

Solution

Create a custom Sphinx extension that adds a HTML context event to override the pageurl variable, which is used by Furo to generate the canonical URL.

Demo

https://overwrite-canonical-without.devportal.pages.dev/
<link rel="canonical" href="https://docs.aiven.io/">

https://overwrite-canonical-without.devportal.pages.dev/docs/platform
<link rel="canonical" href="https://docs.aiven.io/docs/platform">

[cloudflare-workers-and-pages]

Deploying with    Cloudflare Pages

Latest commit:	38f786a
Status:	✅  Deploy successful!
Preview URL:	https://0328b3ad.devportal.pages.dev
Branch Preview URL:	https://overwrite-canonical-without.devportal.pages.dev

View logs

[celestehorgan]

Hi @angelinekwan!

I did the following:

1. Navigated to https://docs.aiven.io/docs/products/redis/concepts/high-availability-redis and confirmed the incorrect canonical URL, https://docs.aiven.io/docs/products/redis/concepts/high-availability-redis.html
2. Navigated to https://overwrite-canonical-without.devportal.pages.dev/docs/products/redis/concepts/high-availability-redis and confirmed the correct canonical URL, https://docs.aiven.io/docs/products/redis/concepts/high-availability-redis.

This LGTM!