Startpage: Please add some introduction

[guettli]

I look at this page: https://proxy.jmap.io/

This is the first text I read:

The JMAP proxy is a work in a progress. It is currently stable enough to test out and get a feel for JMAP in action. All the methods in the spec are implemented, though some atomic guarantees are not possible with other users accessing your servers at the same time

Please start with an introduction. What is JMAP proxy all about? Then the details about the state (work in progress).

Related: https://github.com/guettli/programming-guidelines#love-your-docs

[brong]

Good timing - I'm planning to do some work on the proxy during the hackathon at IETF in Singapore this weekend :)

[bam80]

Update?