Development guide for Si only mentions Al version

version: Silicon
page: developer-guides/developing-apps-on-the-opendaylight-controller

https://docs.opendaylight.org/en/stable-silicon/developer-guides/developing-apps-on-the-opendaylight-controller.html

This "stable-silicon" documentation page only lists the Aluminum version of the sample app. I.e., it shows `1.4.0-SNAPSHOT` but `1.5.0-SNAPSHOT` for Silicon is not listed. Also, when I tried filling in 1.5.0-SNAPSHOT, it did not work.

So this is a two part issue

1. Please update the stable-silicon page to reflect the actual Silicon version of ODL
2. Please release a version (snapshot or otherwise) for Silicon app development.