In-product documentation link for configuring SSL points to the wrong page

Created by: ajaynz

Describe the issue

When you install Sourcegraph for the first time and log into sourcegraph a banner popups up on top of the page requesting the admin user to configure https (see screenshot). Clicking on the banner goes to https://docs.sourcegraph.com/admin/nginx which is no longer valid

Update the hyperlink to point from https://docs.sourcegraph.com/admin/nginx to https://docs.sourcegraph.com/admin/http_https_configuration