Fixed broken links to console access management page

[vonNiklasson]

Previously the pages and files below included a broken link to the Console Access Management page:

• https://registry.terraform.io/providers/cockroachdb/cockroach/latest/docs
• /docs/index.md
• /README.md

The broken link was pointing to

https://www.cockroachlabs.com/docs/cockroachcloud/console-access-management#api-access

but by adding .html as suffix on the url, the link now works again:

https://www.cockroachlabs.com/docs/cockroachcloud/console-access-management.html#api-access