Suggest adding `resourceUrlTemplate` to wiki

[Amar1729]

We were running into 404 errors in VSCode network.log on start, after modifying product.json. Updating the resourceUrlTemplate fixed these issues. Looks like support was added a while back (related issue #432). We ended up actually finding the fix from these issues on the GitLab fork of VSCode:

• https://gitlab.com/gitlab-org/gitlab-web-ide-vscode-fork/-/issues/9
• https://gitlab.com/gitlab-org/gitlab-web-ide-vscode-fork/-/issues/20

Suggest updating the wiki page's to include the following:

    "resourceUrlTemplate": "https://open-vsx.org/api/{publisher}/{name}/{version}/file/{path}"

Weirdly, this field is kind of optional - VSCode can still connect to, install from, and search the OpenVSX marketplace. However this setting gets ride of a lot of the 404's that pop up in the log that seem to be related to searching for auto-updates or fetching resources of installed extensions.

[harsh-k7]

I prepared a documentation update for the OpenVSX wiki
to document the resourceUrlTemplate configuration.

Since GitHub wikis do not support pull requests,
sharing the proposed content here for review:

---

resourceUrlTemplate

Some clients may encounter 404 errors when downloading extension resources.
To avoid this, configure:

'''

Using-Open-VSX-in-VS-Code.md

json
"resourceUrlTemplate": "https://open-vsx.org/api/{publisher}/{name}/{version}/file/{path}"