envoy: docs: getting started with lua config is not easy

I started with Envoy today and my first goal is to get a simple Lua filter working. I hit some hurdles, so I wanted to capture some feedback:

• At first, I was looking in v2, but I learned I need v1 API config.
• I now understand where an HTTP filter goes, but it took me probably 15-20 minutes to understand how to navigate the docs to figure out where a Lua filter goes.
• The “Download” page uses “lyft/envoy:latest” which (I think) doesn’t support Lua yet, so I got errors about an unrecognized filter. I switched to “envoyproxy/envoy”.
• While trying to debug the version issue in the previous point, I was surprised to find that both docker hub and ./envoy --version report commit hashes, but the release notes report version names 1.5.

Ideas for improvement:

• Examples of config starting at the root for each type of entity (e.g. lua filter) would have given me a good picture of the config in one place.
• Don’t use lyft:envoy
• Tag versions by name (e.g. v1.5) in addition to commit hashes
• Report both version name and commit hash in ./envoy --version

I won’t be offended if this issue is closed without action. In my projects, I find it hard to know if people find my docs confusing and really appreciate any feedback on them, so I wanted to capture my experience here.

Really stoked to use Envoy! Thanks!